Are Taller Players the Future of Tennis?

This is a guest post by Wiley Schubert Reed.

This week, the Memphis Open features the three tallest players ever to play professional tennis: 6-foot-10″ John Isner, 6-foot-11″ Ivo Karlovic, and 6-foot-11″ Reilly Opelka. And while these three certainly stand out among all players in the sport, they are by no means the only giants in the game. Also in the Memphis draw: 6-foot-5″ Dustin Brown, 6-foot-6″ Sam Querrey, and 6-foot-8″ Kevin Anderson. (Brown withdrew due to injury, and with Opelka’s second-round loss yesterday, Isner and Karlovic are the only giants remaining in the field.)

We got tall guys. #MemphisOpen

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There is no denying that the players on the ATP and WTA tours are taller than the ones who were competing 25 years ago. The takeover by the tall has been obvious for some time in the men’s game, and it’s extended to near the very top of the women’s game as well. But despite alarms raised about the unbeatable giants among men, the merely tall men have held on to control of the game.

The main reason: The elegant symmetry at the game’s heart. The tallest players have an edge on serve, but that’s just half of tennis. And on the return, extreme height–at least for the men–turns out to be a big disadvantage. But a rising crop of tall men have shown promise beyond their service games. If one of the tallest young stars is going to challenge the likes of Novak Djokovic and Andy Murray, he’ll have to do it by trying to return serve like them, too.

Sorting out exactly how much height helps a player is a complicated thing. Just looking at the top 100 pros, for instance, makes the state of things look like a blowout win in favor of the tall. The median top-100 man is nearly an inch taller today than in 1990, and the average top-100 woman is 1.5 inches taller [1]. The number of extremely tall players in the top 100 has gone up, too:

                                    1990  Aug 2016  
Top 100 Men      Median Height  6-ft-0.0  6-ft-0.8  
               At least 6-ft-5        3%       16%  
Top 100 Women    Median Height  5-ft-6.9  5-ft-8.5  
                 At least 6-ft        8%        9%

Height is clearly a competitive advantage, as taller young players rise faster through the rankings than their shorter peers. Among the top 100 juniors each year from 2000 to 2009 [2], the tallest players (6-foot-5 and over for men and 6-foot and over for women) [3] typically sit in the middle of the rankings. But they do better as pros: They were ranked on average approximately 127 spots higher than shorter players their age after four years for men and approximately 113 spots higher after four years for women.

Boys' pro ranking by height Girls' pro ranking by height

 

Thus, juniors who are very tall have the best chance to build a solid pro career. But does that advantage hold within the top 100 of the pro rankings? Are the tallest pros the highest ranked? 

For the women, they clearly are. From 1985 to 2016, the median top 10 woman was 1.2 inches taller than the median player ranked between No. 11 and No. 100, and the tallest women are winning an outsize portion of titles, with women 6-foot and taller winning 15.0 percent of Grand Slams, while making up only 6.6 percent of the top 100 over the same period. Most of these wins were by Lindsay Davenport, Venus Williams and Maria Sharapova. Garbiñe Muguruza became the latest 6-foot women’s champ at the French Open last year [4]. 

It’s a different story for the men, however. From 1985 to 2016, the median height of both the top 10 men and men ranked No. 11 to No. 100 was the same: 6-foot-0.8. And in those same 32 years, only three Grand Slam titles (2.4 percent) were won by players 6-foot-5 or taller (one each by Richard Krajicek, Juan Martin del Potro and Marin Cilic), while over the same period, players 6-foot-5 and above made up 7.7 percent of the top 100. In short, the tallest women are overperforming, while the tallest men are underperforming.

Why have all the big men accomplished so little collectively? One big reason is that whatever edge the tallest men gain in serving is cancelled out by their disadvantage when returning serve. I compared total points played by top-100 pros since 2011, and found that while players 6-foot-5 and over have a clear service advantage and return disadvantage, their height doesn’t seem to have a major impact on overall points won:

Height            % Svc Pts Won  % Ret Pts Won  % Tot Pts Won  
6-ft-5 and above          66.8%          35.7%          51.2%  
6-ft-1 to 6-ft-4          64.5%          37.8%          51.1%  
6-ft-0 and below          62.3%          39.1%          51.1%

Taller players serve better for two reasons. First, their height lets them serve at a sharper angle by changing the geometry of the court. With a sharper angle available to them, they have a greater margin for error to clear the top of the net while still getting the ball to bounce on or inside the service line. And a sharper angle also makes the ball bounce higher, up and out of returners’ strike zone [5].

Serve trajectory

Disregarding spin, for a 6-foot player to serve the ball at 120 miles per hour at the same angle as a 6-foot-5 player, he would need to stand more than 3 feet inside the baseline.

Second, a taller player’s longer serving arm allows him to whip the ball faster. For you physics fans, the torque (in this case magnitude of force imparted on the ball) is directly proportional to the radius of the lever arm (in this case the server’s extended arm and racket). As radius (arm length) increases, so does torque. There is no way for shorter players to make up this advantage. Six-foot-8 Kevin Anderson, current No. 74 in the world and one of the tallest players ever to make the top 10, told me, “I always say it’ll be easier for me to move like Djokovic than it will be for Djokovic to serve like me.”

One would think that height could be an advantage on return as well, with increased wingspan offering greater reach. 18-year-old, 6-foot-11 Reilly Opelka, who is already as tall as the tour’s reigning giant Ivo Karlovic and who ESPN commentator Brad Gilbert said will be “for sure the biggest ever,” told me his height gives him longer leverage. “My reach is a lot longer than a normal tennis player, so I’m able to cover a couple extra inches, which is pretty huge in tennis.”

But Gilbert and Tennis Channel commentator Justin Gimelstob said they believe tall players struggle on return because their higher center of gravity hurts their movement. If a very tall man can learn to move like the merely tall players that have long dominated the sport––Djokovic, Murray (6-foot-3), Roger Federer (6-foot-1) and Rafael Nadal (6-foot-1)–– Gilbert thinks he could be hard to stop. “If you’re 6-foot-6 and are able to move like that, I can easily see that size dominating,” he said.

Interestingly, Gilbert pointed out that some of the best returners in the women’s game––such as Victoria Azarenka (6-foot-0) and Maria Sharapova (6-foot-2)––are among its tallest players [6]. Carl Bialik asked three American women — 5-foot-11 Julia Boserup, 5-foot-10 Jennifer Brady and 5-foot-4 Sachia Vickery — why they think taller women aren’t at a disadvantage on return. They cited two main reasons: 1) Women are returning women’s serves, which are slower and have less spin, on average, than men’s serves, so they have more time to make up for any difficulty in movement; and 2) Women play on the same size court that men do, but a height that’s relatively tall for a woman is about average for men, and it’s a height that works well for returning, no matter your gender.

“On the women’s side, we don’t really have anyone who’s almost 6-foot-11 or 7-foot tall,” Brady said. While she’s above average height on the women’s tour, “I’m not as tall as Reilly Opelka,” she said.

Another reason players as tall as Opelka tend to struggle on return could be that they focus more in practice on improving their service game, which exacerbates the serve-oriented skew of their games. “Being tall helps with the serve and you maybe tend to focus on your serve games even more,” Karlovic, the tallest top 100 player at 6-foot-11 [7], said in an interview conducted on my behalf by members of the ATP World Tour PR & Marketing staff at the Bucharest tournament in April. “Shorter players aren’t as strong at serve so they work their return more.”

Charting the careers of all active male players 6-foot-5 and above who at some point ranked year-end top 100 bears this out. Their percentage of service points won increased by about 6 percentage points over their first eight years on tour [8], while percentage of return points won only increased by about 1.5 percentage points. In contrast, Novak Djokovic has steadily improved his return points won from 36.7 percent in 2005 to 43.9 percent in 2016.

When very tall men break through, it’s usually because of strong performance on return: del Potro and Cilic, who are both 6-foot-6, boosted their return performances to win the US Open in 2009 and 2014, respectively. At the 2009 US Open, del Potro won 44 percent of return points, up from his 40 percent rate on the whole year, including the Open. At the 2014 US Open, Cilic won 41 percent of return points, up from 38 percent that year. And they didn’t improve their return games by facing easy slates of opponents: Each man improved on his return-point winning rates against those same opponents over his career by about the same amount as he elevated his return game compared to the season as a whole.

“It’s a different type of pressure when you’re playing a big server who is putting pressure on you on both the serve and the return,” Gimelstob said. “That’s what Cilic was doing when he won the US Open. That’s the challenge of playing del Potro because he hits the ball so well, but obviously serves so well, also.” To put things into perspective, if del Potro and Cilic had returned at these levels across 2016, each would have ranked among the top seven returners in the game, joining Djokovic, Nadal, Murray, 5-foot-11 David Goffin, and 5-foot-9 David Ferrer. Neither man, though, has been able to return to a Slam final; del Potro has struggled with injury and Cilic with inconsistency.

For the tallest players, return performance is the difference between making the top 50 and the top 10. On average, active players 6-foot-5 and above who finished a year ranked in the top 10 won 67.7 percent of service points that year, while those who finished a year ranked 11 through 50 won 68.1 percent of service points, on average. That’s a difference of only 0.4 percentage points. The difference in return performance between merely making the top 50 and reaching the top 10, however, is far more striking: Tall players who made the top 10 win return points at a rate nearly 4 percentage points higher than do players ranked 11 through 50.

Tall players' points won

A solid-serving player 6-foot-5 or taller who can consistently win more than 38 percent of points on return has an excellent chance of making the top 10. Tomas Berdych and del Potro have done it, and Milos Raonic is approaching that mark, one reason he reached his first major final this year at Wimbledon. Today there are several tall young men who look like they could eventually win 38 percent of return points or better. Alexander Zverev (ranked 18) and Karen Khachanov (ranked 48) are both 6-foot-6, each won about 38 percent of return points in 2016, and neither is older than 20. Khachanov has impressed Gilbert and Karlovic. “That guy moves tremendous for 6-foot-6,” Gilbert said.

Other giants have impressed recently. Jiri Vesely, who is 23 and 6-foot-6, beat Novak Djokovic last year in Monte Carlo and won nearly 36 percent of return points in 2016. Opelka reached his first tour-level semifinal, in Atlanta. Most of the top 10 seeds at Wimbledon lost to players 6-foot-5 or taller. Del Potro won Olympic silver, beating Djokovic and Nadal along the way.

But moving from the top 10 to the top 1 or 2 is another question. Can a taller tennis player develop the skills to move as well as the top shorter players, and win multiple major titles? Well, it’s happened in basketball. “We haven’t had a big guy play tennis that’s like 6-foot-6, 6-foot-7, 6-foot-8, that’s moved like an NBA guy,” Gilbert said. “When you get that, that’s when you get a multiple Slam winner.” Anderson agrees that height is not the obstacle to movement people play it up to be: “You know, LeBron is 6-foot-8. If he can move as well as somebody who’s 5-foot-10, his size now is a huge advantage; there’s not a negative to it.”

Opelka, who qualified for his first grand slam main draw at the 2017 Australian Open where he pushed 11th-ranked David Goffin to five sets, says he is specifically focusing on the return part of his game in practice. “I’ve been spending a ton of time working on my return. When you look at the drills I’m doing in the gym, they work on explosive movement.” But he also points out that basketball players “move better than [tennis players] and are more explosive than [tennis players]” because of their incredible muscle mass, which won’t work for tennis. “I don’t know how they’d be able to keep up for four or five hours with that mass and muscle.” Put LeBron on Arthur Ashe Stadium at the U.S. Open in 100 degree heat for an afternoon, “it’s tough to say how they’ll compare.”

Zverev, who is 19 and 6-foot-6, agrees that tall tennis players face unique challenges: “Movement is much more difficult, and I think building your body is more difficult as well.” But the people I talked to believe that both Opelka and Zverev could be at the top of the game in a few years’ time. “Zverev––that guy could be No. 1 in the world,” Gilbert said. “He serves great, he returns great and he moves great.” And as for Opelka, Gilbert says: “Right now he’s got a monster serve. If he can develop movement, or a return game, who knows where he could go?”

Whether the tallest guys can develop the skills to consistently return at the level of a Djokovic or a Murray remains to be seen. But starting out with a huge serve is a major step toward eventually challenging them. As Opelka says, “every inch is important.”

 

Wiley Schubert Reed is a junior tennis player and fan who has written about tennis for fivethirtyeight.com. He is a senior at the United Nations International School in New York and will be entering Harvard University in the fall.

 

Continue reading Are Taller Players the Future of Tennis?

Can Nick Kyrgios Win a Grand Slam?

Today’s breaking news? Former Wimbledon finalist Mark Philippoussis thinks that Nick Kyrgios can win the Australian Open. Hey, it’s almost the offseason. We take our news wherever we can get it.

Still, it’s an interesting question. Is it possible for such a volatile, one-dimensional player to string together seven wins on one of the biggest stages in the sport? Philippoussis–not the most versatile of players himself–reached two Slam finals. A big serve can take you far.

Last year, I published a post investigating the “minimum viable return game,” the level of return success that a player would need to maintain in order to reach the highest echelon of men’s tennis. It’s rare to finish a season in the top ten without winning at least 38% of return points, though a few players, including Milos Raonic, have managed it. When I wrote that article, Kyrgios’s average for the previous 52 weeks was a measly 31.7%, almost in the territory of John Isner and Ivo Karlovic.

Kyrgios has improved since then. In 2016, he won 35.4% of return points, almost equal to Raonic’s 35.9%–and most would agree that Milos had an excellent year. Philippoussis’s career mark was only 34.9%, though Kyrgios would be lucky to play as many tournaments on grass and carpet as Philippoussis did. Still, a sub-36% rate of return points won isn’t usually good enough in today’s game: Raonic was only the third player since 1991 (along with Pete Sampras and Goran Ivanisevic) to finish a season in the top five with such a low rate.

Then again, Philippoussis didn’t say anything about finishing in the top five. The “minimum viable Slam-winning return game” might be different. Looking at all Grand Slam champions back to 1991, here are the lowest single-tournament rates of return points won:

Year  Slam             Player               RPW%                     
2001  Wimbledon        Goran Ivanisevic    31.1%  
1996  US Open          Pete Sampras        32.8%  
2009  Wimbledon        Roger Federer       33.7%  
2002  US Open          Pete Sampras        35.6%  
2000  Wimbledon        Pete Sampras        36.6%  
2010  Wimbledon        Rafael Nadal        36.8%  
2014  Australian Open  Stan Wawrinka       37.0%  
1998  Wimbledon        Pete Sampras        37.2%  
1991  Wimbledon        Michael Stich       37.4%  
2000  US Open          Marat Safin         37.5%

Wimbledon is well-represented here, as we might expect. Not so for Kyrgios’s home Slam: Stan Wawrinka‘s 2014 Australian Open title is the only time it appears in the top 20, even though it has played very fast in recent years. Every other Melbourne titlist won at least 39.5% of return points. As with year-end top-ten finishes, 38% is a reasonable rule of thumb for the minimum viable level, though on rare occasions, it is possible to come in below that.

The bar is set: Can Kyrgios clear it? 18 months ago, when Kyrgios’s 52-week return-points-won average was below 32%, the obvious answer would have been negative. His current mark above 35% makes the question a more interesting one. To win a Slam, he’ll probably need to return better, but only for seven matches.

The Australian has enjoyed one seven-match streak–in fact, a nine-match run–that would be more than good enough. Combining his title in Marseille and his semifinal showing in Dubai this Februrary, Kyrgios played almost nine matches (he retired with a back injury in the last one) while winning a whopping 41.5% of return points. At 42 of the last 104 Slams, the champion has won return points at a lower rate.

However, February was an aberration. To approximate Kyrgios’s success over the length of a Slam, I looked at his return points won over every possible streak of ten matches. (Most of his matches have been best-of-three, so ten matches is about the same number of points as a Slam title run.) Aside from the streaks involving Marseille and Dubai this year, he has never topped 37% for that length of time.

There’s always hope for improvement, especially for a mercurial 21-year-old in a sport dominated by older men. But the evidence is against him here, as well. Research by falstaff78 suggests that players do not substantially improve their return statistics as they mature. That may seem counterintuitive, since some players clearly do develop their skills. However, as players get better, they go deeper in tournaments and alter their schedules, changing the mix of opponents they face. Two years ago, Kyrgios faced seven top-20 players. This year he played 18. Raonic, who represents an optimistic career trajectory for Kyrgios, faced 26 this season.

Against the top 20–the sorts of Grand Slam opponents a player has to beat to get from the fourth round to the trophy ceremony–Kyrgios has won less than 30% of his career return points. Even Raonic, who has yet to win a Slam himself, has done better, and won 32.6% of return points against top-20 opponents this year.

There’s little doubt that Kyrgios has the serve to win Grand Slams. And once the Big Four retire, I suppose someone will have to win the majors. But even in weak eras, you need to break serve, and at Slams, you typically need to do so many times, and against very high-quality opponents. The evidence we have so far strongly implies that Kyrgios, like Philippoussis before him, will struggle to triumph at a Slam.

Andy Murray and the Longest Break-Per-Match Streaks

Among Andy Murray‘s many accomplishments in 2016, he achieved an impressive–though obscure–feat. In each one of his 87 matches, he broke serve at least once. He has broken at least once per match since failing to do so against Roger Federer in the 2015 Cincinnati semifinals, for an active streak of 107 matches.

Where does that place him among the greats of men’s tennis? Just how unusual is it to break serve in every match for an entire season? As is the case with too many tennis statistics, we don’t know. Someone finds an impressive-sounding stat, and that’s the end of the story. We can’t always fix that, but in this case, we can add some context to Murray’s accomplishment.

Full break-per-match seasons

I’ve collected break stats for matches back to 1991, though we need to keep in mind that there are some mistakes in the 1990s data. Further, Davis Cup presents a problem, as it is excluded entirely. Sometimes we can tell from the scoreline that a player broke serve–as with all of Murray’s Davis Cup matches this year–but often we cannot. I’ll have more to say about that in specific cases below.

Since 1991, there have been at least 14, and perhaps as many as 20 instances in which a player broke serve in every match of a season. (Minimum 40 tour-level matches, and I’ve excluded retirements when calculating both minimums and the streaks themselves.) I say “instances” because several players–Andre Agassi, Lleyton Hewitt, Rafael Nadal, and Nikolay Davydenko–pulled it off more than once. Hewitt’s 2001 season had the most matches–95–of any of them, followed by Murray’s 2016 and Nadal’s 2005, at 87 each.

Here is the complete list:

Player                  Season  Matches  (Unsure)  
Andy Murray               2016       87         0  
Juan Monaco               2014       41         0  
Novak Djokovic            2013       83         0  
Rafael Nadal              2010       79         0  
Nikolay Davydenko         2008       73         0  
Nikolay Davydenko         2007       82         0  
Lleyton Hewitt            2006       46         0  
Rafael Nadal              2005       87         0  
David Nalbandian          2005       63         0  
Andre Agassi              2003       55         0  
Lleyton Hewitt            2001       95         0  
Lleyton Hewitt            2000       76         1  
Hernan Gumy               1997       53         1  
Alex Corretja             1997       67         0  
Andre Agassi              1995       81         0  
Magnus Gustafsson         1994       40         0  
Carlos Costa              1992       60         0  
Guillermo Perez Roldan    1991       40         2  
Ivan Lendl                1991       72         0  
Boris Becker              1991       61         2

(The “Unsure” column indicates how many matches are missing stats and may not have included a break of serve.)

Several more players came close. Federer broke serve in all but one match in three separate seasons. Agassi, Novak Djokovic, David Ferrer, and Thomas Muster all did so twice.

We shouldn’t be surprised that so many players–especially the greats–have broken so often. It’s very rare to win a match without breaking serve: Of the 2,570 ATP tour-level matches from this season for which I have match stats, the winner broke serve in all but 30 of them. Even losers break serve in more than two out of every three matches: In 2016, the loser broke serve in 1,843 of the 2,570 matches, 72% of the time.

Still, there are enough dominant servers on tour that it is difficult to last an entire season without being shut out of the break column. In 1995, Muster broke serve in 99 matches, but failed to do so when he drew the big-serving (and completely unheralded) qualifier TJ Middleton on the carpet in St. Petersburg. Murray’s current streak is all the more impressive because, in his 107 matches, he has faced Milos Raonic six times, John Isner four times, Kevin Anderson and Nick Kyrgios twice each, and Ivo Karlovic once. Given the chance, he probably would’ve broken TJ Middleton as well.

Break-per-match streaks

For Murray to surpass the longest streaks in this category, it will take several more months of high-quality returning. As we saw above, Davydenko and Hewitt may have gone two full years breaking serve in every match they played. In both cases, the lack of ITF data makes their records unclear, but regardless of those details, Davydenko has set an extremely high bar.

Here are all the break-per-match streaks of 100 or more matches since 2000:

Player             Start   End  Streak  Possible  
Nikolay Davydenko   2006  2009     159       182  
Rafael Nadal        2004  2006     156            
Rafael Nadal        2009  2011     146            
Andre Agassi        2002  2004     143            
Novak Djokovic      2012  2014     127            
Lleyton Hewitt      1999  2002     124       230  
Andy Murray         2015  2016     107         ∞  
David Nalbandian    2004  2006     104

This season, Murray didn’t play his 53rd match until August at the Olympics; he’ll need to break serve at least once in that many matches to reach the top of this list.

The exact length of Davydenko’s streak hinges on his 2008 Davis Cup semifinal match against Juan Martin del Potro, which he lost in straight sets. If he broke serve in that match, his streak stretched into early 2009, spanning 182 matches.

(Edit: Thanks to Andrew Moss, we now know that Davydenko did break serve in that match, according to this contemporaneous report.)

Hewitt’s best streak is even more unclear. I don’t have break stats for his 6-3 6-3 loss to Max Mirnyi at the 2000 Olympics. If he didn’t break Mirnyi–a definite possibility, given The Beast’s serving prowess–the streak is “only” 124 matches. If he did, the streak is at least 187, and the exact length depends on more unknowns, including both of his singles matches in the 1999 Davis Cup final against France.

(Edit #2! Thanks to Carl, we know that Hewitt broke Mirnyi, so his streak is at least 187 matches. The next issue is his last match of the 1999 season, a dead rubber against Sebastian Grosjean in that year’s Davis Cup final. Hewitt lost 6-4 6-3, but Grosjean was hardly an overpowering server. Hewitt lost his previous Davis Cup match in straight sets as well, a live rubber against Cedric Pioline, and a match report establishes that Hewitt broke serve. If he broke Grosjean, the streak stretches back to April 1999, and numbers the full 230 matches.)

In any case, Murray has already earned himself a place among the greatest returners in modern tennis. In 2017, we’ll see just how far he can climb this list.

Is Milos Raonic’s Return Game Improving?

It’s no secret that Milos Raonic‘s return game is a liability. He has reached the game’s elite level with a dominant serve, and he broke into the top five on the strength of a historically-great record in tiebreaks.

Last year, Raonic’s tiebreak record fell back to earth (as these things usually do) and he dropped out of the top ten. Now, in a new season with a new coach, Carlos Moya, Raonic reeled off nine straight victories, finally losing in five sets to Andy Murray in today’s Australian Open semifinal.

Until today’s match, when Raonic won a dismal 25% of return points, the numbers were looking good. Milos won 36.5% of return points in his four matches in Brisbane, which is a little bit better than the 35% tour average on hard courts. With his serve, he doesn’t need to be a great returner; simply improving that aspect of his game to average would make him a dominant force on tour.

This is a crucial number to watch, because it could be the difference between Milos becoming number one in the world and Milos languishing in the back half of the top ten. It’s incredibly rare that players with weak return games are able to maintain a position at the very top of the rankings.

Through the quarterfinals in Melbourne, the positive signs kept piling up. For each of his 2016 opponents, I tallied their 2015 service points won on hard courts. In 6 of 10 matches this month, Milos kept their number below their 2015 average. In a 7th match, against Gael Monfils, he was one return point away from doing the same.

By comparison, in 2015, Raonic held hard-court opponents to their average rate of service points won only 9 times in 35 tries. Even in his career-best season of 2014, he did so in only 15 of 41 matches. Even with the weak return numbers against Murray, this is Raonic’s best ever 10-match stretch, by this metric.

The difference is more dramatic when we combine all these single-match measurements into a single metric per season. For each match, I calculated how well Milos returned relative to an average player against his opponent that day. For example, against Murray today, he won 25% of return points compared to an average hard-court Murray opponent’s 33.7%. In percentage terms, Raonic returned 26% worse than average.

Aggregating all of his 2016 matches, Raonic has returned 6% better than average. In 2015 hard-court matches, he was 10% below average; in 2014, 3% below average, and in 2013, 7% below average.

A nine-match stretch of good form is hardly proof that a player has massively improved half of his game, but it’s certainly encouraging. While all know that Milos is an elite server, it’s his return game that will determine how great he becomes.

Winning Return Points When It Matters

In my post last week about players who have performed better than expected in tiebreaks (temporarily, anyway), I speculated that big servers may try harder in tiebreaks than in return games.

If we interpret “try harder” as “win points more frequently,” we can test it. With my point-by-point dataset, we can look at every top player in the men’s game and compare their return-point performance in tiebreaks to their return-point performance earlier in the set.

As it turns out, top players post better return numbers in tiebreaks than they do earlier in the set. I looked at every match in my dataset (most tour-level matches from the last few seasons) for the ATP top 50, and found that these players, on average, won 5.2% more return points than they did earlier in those sets.

That same group of players saw their serve performance decline slightly, by 1.1%. Since the top 50 frequently play each other, it’s no surprise that the serve and return numbers point in different directions. However, the return point increase and the serve point decrease don’t cancel each other out, suggesting that the top 50 is winning a particularly large number of tiebreaks against the rest of the pack, mostly by improving their return game once the tiebreak begins.

(There’s a little bit of confirmation bias here, since some of the players on the edge of the top 50 got there thanks to good luck in recent tiebreaks. However, most of top 50–especially those players who make up the largest part of this dataset–have been part of this sample of players for years, so the bias remains only minor.)

My initial speculation concerned big servers–the players who might reasonably relax during return games, knowing that they probably won’t break anyway. However, big servers aren’t any more likely than others to return better in tiebreaks. (Or, put another way, to return worse before tiebreaks.) John Isner, Ivo Karlovic, Kevin Anderson, and Roger Federer all win slightly more return points in tiebreaks than they do earlier in sets, but don’t improve as much as the 5.2% average. What’s more, Isner and Anderson improve their serve performance for tiebreaks slightly more than they do their return performance.

There are a few players who may be relaxing in return games. Bernard Tomic improves his return points won by a whopping 27% in tiebreaks, Marin Cilic improves by 16%, and Milos Raonic improves by 11%. Tomic and Raonic, in particular, are particularly ineffective in return games when they have a break advantage in the set (more on that in a moment), so it’s plausible they are saving their effort for more important moments.

Despite these examples, this is hardly a clear-cut phenomenon. Kei Nishikori, for example, ups his return game in tiebreaks almost as much as Cilic does, and we would never think of him as a big server, nor do I think he often shows signs of tactically relaxing in return games. We have plenty of data for most of these players, so many of these trends are more than just statistical noise, but the results for individual players don’t coalesce into any simple, overarching narratives about tiebreak tendencies.

There is one nearly universal tendency that turned up in this research. When leading a set by one break or more, almost every player returns worse. (Conversely, when down a break, almost every player serves better.) The typical top 50 player’s return game declines by almost 5%, meaning that a player winning 35% of return points falls to 33.4%.

Almost every player fits this pattern. 48 of the top 50–everyone except for David Ferrer and Aljaz Bedene–win fewer return points when up a break, and 46 of 50 win more service points when down a break.

Pinning down exactly why this is the case is–as usual–more difficult than establishing that the phenomenon exists. It may be that players are relaxing on return. A one-break advantage, especially late, is often enough to win the set, so it may make sense for players to conserve their energy for their own service games. Looking at it from the server’s perspective, that one-break disadvantage might remove some pressure.

What’s clear is this: Players return worse than usual when up a break, and better than usual in tiebreaks. The changes are much more pronounced for some ATPers than others, but there’s no clear relationship with big serving. As ever, tiebreaks remain fascinating and more than a little inscrutable.

Toward a Better Understanding of Return Effectiveness

The deeper the return, the better, right? That, at least, is the basis for many of the flashy graphics we see these days on tennis broadcasts, indicating the location of every return, often separated into “shallow,” “medium,” and “deep” zones.

In general, yes, deep returns are better than shallow ones. But return winners aren’t overwhelmingly deep, since returners can achieve sharper angles if they aim closer to the service line. There are plenty of other complicating factors as well: returns to the sides of the court are more effective than those down the middle, second-serve returns tend to be better than first-serve returns, and topspin returns result in more return points won than chip or slice returns.

While most of this is common sense, quantifying it is an arduous and mind-bending task. When we consider all these variables–first or second serve, deuce or ad court, serve direction, whether the returner is a righty or lefty, forehand or backhand return, topspin or slice, return direction, and return depth–we end up with more than 8,500 permutations. Many are useless (righties don’t hit a lot of forehand chip returns against deuce court serves down the T), but thousands reflect some common-enough scenario.

To get us started, let’s set aside all of the variables but one. When we analyze 600+ ATP matches in the Match Charting Project data, we have roughly 61,000 in-play returns coded in one of nine zones, including at least 2,000 in each.  Here is a look at the impact of return location, showing the server’s winning percentage when a return comes back in play to one of the nine zones:rzones1show

(“Shallow” is defined as anywhere inside the service boxes, while “Medium” and “Deep” each represent half of the area behind the service boxes. The left, center, and right zones are intended to indicate roughly where the return would cross the baseline, so for sharply angled shots, a return might bounce shallow near the middle of the court but be classified as a return to the forehand or backhand side.)

As we would expect, deeper returns work in favor of the returner, as do returns away from the center of the court. A bit surprisingly, returns to the server’s forehand side (if he’s a right-hander) are markedly more effective than those to the backhand. This is probably because right-handed returners are most dangerous when hitting crosscourt forehands, although left-handed returners are also more effective (if not as dramatically) when returning to that side of the court.

Let’s narrow things down just a little and see how the impact of return location differs on first and second serves. Here are the server’s chances of winning the point if a first-serve return comes back in each of the nine zones:

rzones2showF

And the same for second-serve returns:

rzones3showF

It’s worth emphasizing just how much impact a deep return can have. So many points are won with unreturnable serves–even seconds–that simply getting the ball back in play comes close to making the point a 50/50 proposition. A deep second-serve return, especially to a corner, puts the returner in a very favorable position. Consistently hitting returns like that is a big reason why Novak Djokovic essentially turns his opponents’ second serves against them.

The final map makes it clear how valuable it is to move the server away from the middle of the court. Think of it as a tactical first strike, forcing the server to play defensively instead of dictating play with his second shot. Among second-serve returns put in play, any ball placed away from the middle of the court–regardless of depth–gives the returner a better chance of winning the point than does a deep return down the middle.

For today, I’m going to stop here. This is just the tip of the iceberg, as there are so many variables that play some part in the effectiveness of various service returns. Ultimately, understanding the potency of each return location will give us additional insight into what players can achieve with different kinds of serve, which players are deadliest with certain types of returns, and how best to handle different returns with the server’s crucial second shot.

Is Kevin Anderson Developing Into an Elite Player?

With his upset win over Andy Murray on Monday, Kevin Anderson reached his first career Grand Slam quarterfinal. At age 29, he’ll ascend to a new peak ranking, and with a bit of cooperation from the rest of the draw, one more win could put him in the top ten for the first time.

Anderson has been a stalwart in the top 20 for two years now, but this additional step comes as a bit of a surprise. Despite the overall aging of the ATP tour and the emergence of Stan Wawrinka as a multi-Slam champion, it’s still a bit difficult to imagine a player in his late twenties taking major steps forward in his career.

What’s more, Anderson’s game is very serve-dependent. With an excellent backhand, he isn’t as one-dimensional a player as John Isner, Ivo Karlovic, or perhaps even Milos Raonic, but it’s much easier to categorize him with those players than with more baseline-oriented peers.

In today’s game, it is very difficult to reach the very top ranks without a quality return game. Tiebreaks are too much of a lottery to depend on in the long-term; you have to consistently break serve to win matches. As I wrote in a post about Nick Kyrgios earlier this year, almost no players have finished a season in the top ten without winning at least 37% of return points. Anderson has achieved that mark only once, in 2010. Entering the US Open this year, he was winning only 34.2% of return points.

The only top-ten player this year with a lower rate of return points won is Raonic, at 30.2%. Raonic is a historical anomaly, and as his tiebreak winning percentage has tumbled, from a near-record 75% last year to a more typical 51% this year, his place in the top ten is in jeopardy as well. In other words, the only servebot in the top ten has to rely on plenty of luck–or outstanding, perhaps one-of-a-kind skills in the clutch–to remain among the game’s elite.

Anderson is a more well-rounded player than Raonic, and he wins more return points than that. But he still falls well short of the next-worst return game in the top ten, Wawrinka’s 36.7%. The 2.5 percentage points between Anderson and Wawrinka represent a big gap, almost one-fifth of the entire range between the game’s best and worst returners.

The less effective a player’s return game, the more he must rely on tiebreaks to win sets, and that’s one explanation for Anderson’s success this season. His 62%(26-16) tiebreak winning percentage in 2015 is the best of his career, and considerably higher than his career tiebreak winning percentage of 54%. Again, it sounds like a small difference, but take away three or four of the tiebreaks he’s won this year, and he no longer reached the final at Queen’s Club … or might not be preparing for a quarterfinal in New York.

Very few players have managed to spend meaningful time in the top ten while depending so heavily on winning tiebreaks. Another metric to help us see this is the percentage of sets won that are won in tiebreaks. Entering the US Open, just over 25% of Anderson’s sets won were won in tiebreaks. Only four times since 1991 has a player sustained a rate that high and ended the year in the top ten: Raonic last year, Andy Roddick in 2007 and 2009, and Greg Rusedski in 1998.

In fact, between 1991 and 2014, only 17 times did a player finish a season in the top ten with this rate above 20%. Roddick represents five of those times, and almost all, except for Roddick at his peak, were players who finished outside the top five. Wawrinka’s and Raonic’s 2014 seasons were the only occurrences in the last decade.

The one ray of light in Anderson’s statistical profile this season is a significantly improved first serve. His 2015 ace rate is over 18%, compared to the 2014 (and career average) rate of 14%. His percentage of first-serve points won is up to 78.8%, from last season’s 75.4% and a career average of 75.8%.

This is a major improvement, and is the reason why he is one of only five players on tour (along with Isner, Karlovic, Roger Federer, and Novak Djokovic) winning more than 69% of service points this year. In many ways, Anderson’s stats are similar to those of Feliciano Lopez, but the Spaniard–another player who has long stood on the fringes on the top ten–has never topped 68% of service points won for a full season.

If Anderson can sustain this new level of first-serve effectiveness, he will–at the very least–continue to see a bit more success in tiebreaks. A tiebreak winning percentage higher than his career average of 54% (though still probably below his 2015 rate of 62%) will help keep him in the top 15. However, even for the best servers, tiebreaks are often little more than coin flips, and players don’t join the game’s elite by relying on coin flips.

As his quarterfinal appearance at the Open shows, Anderson is moving in the right direction. It’s easy to see a path for him that involves ending the season in the top ten. But to move up to the level above that, following the path of someone like Wawrinka, he’ll need to start serving like peak Andy Roddick, or–perhaps just as difficult–significantly improve his return game.