Podcast Episode 46: Australian Open Recap

Episode 46 of the Tennis Abstract Podcast, with Carl Bialik of the Thirty Love podcast, focuses on the eye-popping achievements of Australian Open champs Naomi Osaka and Novak Djokovic. With Osaka, we consider how much she has accomplished in a single year, and whether she has distanced herself from the WTA pack. With Djokovic, we wonder how anyone could ever beat him on a hard court, and how high he’ll climb on the all-time grand slam leaderboard.

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The Impact of Rafael Nadal’s New Serve

Italian translation at settesei.it

A couple of years ago, the story of the Australian Open was a certain veteran Swiss player’s new backhand. Roger Federer won the tournament, raced back up the rankings, and eventually reclaimed the No. 1 spot. This season has kicked off with another superstar, Rafael Nadal, attempting to shore up his own relative weakness by streamlining his serve.

The early results are extremely positive. Through the semi-final, Nadal’s first serves in Melbourne have averaged 115 mph, compared to 110 mph at the US Open last fall. He hasn’t been broken in five straight matches, dating back to the second round, and has faced only 13 break points in his last 15 sets. True, he hasn’t faced a truly tough test, as the draw has handed him only two seeds, neither in the top ten. But his lopsided results thus far could equally be ascribed to his own dominance. After all, he demolished Stefanos Tsitsipas only a few days after the Greek prospect ousted Federer.

Serve speed numbers are encouraging and lopsided wins are great for the body, but our focus should always be on points, and how many of them he’s winning. By that measure, Rafa’s retooled serve has excelled, helping the Spaniard post some of the best-ever serving numbers of his grand slam career.

In six matches, Nadal has won 80.9% of his first-serve points. (Fellow finalist Novak Djokovic has won 77.5% of his. Both numbers are outstanding, as the hard-court tour average is below 75%, a figure that includes the contributions of much more dominant servers.) At hard and grass court grand slams, Rafa has done better only twice: 83.6% at the 2010 US Open and 81.3% and Wimbledon in 2008. Here are his top-ten first-serve performances through the semi-finals at hard court majors:

Tournament            1st W%  2nd W%            
2010 US Open           83.6%   66.9%            
2008 Wimbledon         81.3%   64.3%            
2019 Australian Open   80.9%   58.0%            
2013 US Open           79.5%   64.7%            
2017 Wimbledon         79.4%   58.6%            
2011 Wimbledon         79.4%   59.4%            
2010 Wimbledon         79.3%   61.6%            
2006 Wimbledon         77.9%   62.1%            
2012 Wimbledon         77.3%   61.5%            
2012 Australian Open   76.8%   56.7%

You might notice a pattern at the top of this list: Those are slams that he went on to win. The 2010 US Open was his first hard court major title, sealed with a four-set win over Djokovic, his most dominant non-clay victory over his long-time rival. 2008 Wimbledon was his first title there, in the memorable final against Federer. The 2013 US Open was another relatively tidy triumph over Djokovic. All the Wimbledons that clutter the bottom half of this list are inflated a bit by the surface, and it is revealing that Rafa’s next-best performance at the Australian Open sits so far down the list, with his 76.5% first-serve mark in 2012. That fortnight didn’t end in his favor, but it took nearly six hours for Djokovic to beat him.

This is all encouraging and, at the very least, it will make for an interesting aspect of tomorrow’s final, between the newly dangerous serving of Nadal and the ever-brilliant return game of Djokovic. But with only six matches on record, it’s tough to push the analysis much further. Rafa was dominant against Tsitsipas, but barely better than he was against the Greek when they met in Canada last summer. In Australia, he won 80.3% of service points, including 85% of his firsts; in their previous meeting, he won 78.9% of service points and 93.8% of his firsts. A more positive comparison is between his fourth-round win over Tomas Berdych (75.3% service points won, 80.4% firsts) and his previous hard court meetings with the Czech (66.6%, 72.7%). On the other hand, they hadn’t played since 2015 and Berdych is returning from injury, so we can’t put too much weight on the comparison.

Nadal’s more pessimistic fans will be keeping an eye on his second serve in Sunday’s final, as that delivery has not demonstrated the same jump in effectiveness. In the six Melbourne matches, Rafa has won 58.0% of second-serve points, just barely above his career average of 57.3% at hard court majors. That relative weakness was exploited by Alex De Minaur, the best returner of his Aussie Open opponents, who held Nadal to a measly 36.4% of second serve points won. Djokovic is even better, neutralizing bigger second-serve weapons than Rafa’s, so it remains a concern.

If Nadal wins the title, his new serve will rightfully take much of the credit. Not only has it improved his effectiveness on that side of the ball, it has helped keep his matches short and his body ready for the challenges of hard court tennis. Years ago, I bucked the conventional wisdom and argued that Rafa could reach 17 slams. Since then, Federer has shifted the goalposts, but a bigger-serving Nadal makes 20 or 21 look more realistic than ever before.

Petra Kvitova’s Current Status: Low Risk, High Reward

Italian translation at settesei.it

For more a decade, Petra Kvitova has been one of the most aggressive women in tennis. She aims for the corners, hits hard, and lets the chips fall where they may. Sometimes the results are ugly, like a 6-4 6-0 loss to Monica Niculescu in the 2016 Luxembourg final, but when it works, the rewards–two Wimbledon titles, for starters–more than make up for it.

She’s currently riding another wave of winners. Her 11-match win streak–which has involved the loss of only a single set–puts her one more victory away from a third major championship. The 28-year-old Czech has gotten this far by persisting with her big-hitting style, but with a twist: In Melbourne, she’s not missing very often. While she’s ending as many points as ever on her own racket, she’s missing less often than many of her more conservative peers.

In her last five matches at the Australian Open, from the second round through the semi-finals, 7.9% of her shots (including serves) have resulted in unforced errors. In the 88 Petra matches logged by the Match Charting Project, that’s the stingiest five-match stretch of her career. In charted matches since 2010, the average WTA player hits unforced errors on 8.0% of their shots. So Kvitova, the third-most aggressive player on tour, is somehow making errors at a below-average rate. It’s high-risk, high-reward tennis … without the risk.

And it isn’t because her go-for-broke tactics have changed. In Thursday’s semi-final against Danielle Collins, her aggression score–an aggregate measure of point-ending shots including winners, induced forced errors, and unforced errors–was 30.5%, the third-highest of all of her charted matches since her 2017 return to the tour. Her overall aggression score in Melbourne, 28.2%, is also higher than her career average of 27.1%.

In other words, she’s making fewer errors, and the missing errors are turning into point-ending shots in her favor. The following graph shows five-match rolling averages of winners (and induced forced errors) per shot and unforced errors per shot for all charted matches in Kvitova’s career:

Even with the winner and error rates smoothed out by five-match rolling averages, these are still some noisy trend lines. Still, some stories are quite clear. This month, Kvitova is hitting winners at close to her best-ever rate. Her average since the second round in Melbourne has been 20.3%, as high as anything she’s posted before with the exception of her 2014 Wimbledon title. (I’ve never tried to adjust winner totals for surface; it’s possible that the difference can be explained entirely by the grass.)

And most strikingly, this is as big a gap between winner rate and error rate as she’s achieved since her 2014 Wimbledon title run. In fact, between the second round and semi-finals at that tournament, she averaged 8.1% errors and 20.0% winners. Both of her numbers in Australia this year have been a tiny bit better.

Best of all, the error rate has–for the most part–seen a steady downward trend since 2016. The recent error spike is largely due to her three losses in Singapore last October and a bumpy start to this season in Brisbane. We can’t write those off entirely–perhaps Kvitova will always suffer through weeks when her aim goes awry–but she appears to have put them solidly behind her.

None of this is a guarantee that Petra will continue to avoid errors in Saturday’s final against Naomi Osaka. I could’ve written something about her encouraging error rates before the tour finals in Singapore last fall, and she failed to win a round-robin match there. And Osaka is likely to offer a stiffer challenge than any of Kvitova’s previous six opponents in Melbourne, even if her second serve doesn’t. That said, a stingy Kvitova is a terrifying prospect, one with the potential to end the brief WTA depth era and dominate women’s tennis.

The Oddity of Naomi Osaka’s Soft Second Serves

Italian translation at settesei.it

Naomi Osaka has quickly risen to the top of the women’s game on the back of some big hitting, especially a first serve that is one of the fastest in the game. Through Thursday’s semi-final, Osaka’s average first-serve speed in Melbourne was 105 mph, faster than all but two of the other women who reached the third round. Even those two–Aryna Sabalenka and Camila Giorgi–barely edged her out, each with average speeds of 106.

Shift the view to second serves, and Osaka’s place on the list is reversed. While Sabalenka’s typical second offering last week was 90 mph and Giorgi’s was 94, Osaka’s has been a mere 78 mph, the fourth-slowest of the final 32. That mark puts her just ahead of the likes of Angelique Kerber and Sloane Stephens, both whose average first serves are nearly 10 mph slower.

Osaka’s 27 mph gap is the biggest of anyone in this group. The next closest is Caroline Wozniacki’s 23 mph gap, between her 102 mph first serve and 79 mph second serve–both of which are less extreme than the Japanese player’s. Expressed as a ratio, Osaka’s average second serve is only 74% the speed of her typical first. That’s also the widest gap of any third-rounder in Melbourne; Wozniacki is again second-most extreme at 77%.

The following table shows first and second serve speeds, along with the gap and ratio between those two numbers, for a slightly smaller group: women for whom the Australian Open published at least four matches worth of serve-speed data:

Player          Avg 1st  Avg 2nd   Gap  Ratio  
Osaka             105.5     78.5  27.0   0.74  
Keys              105.2     85.4  19.7   0.81  
SWilliams         103.8     88.6  15.2   0.85  
Barty             102.0     88.2  13.7   0.87  
KaPliskova        101.9     80.5  21.4   0.79  
Collins           101.2     82.2  19.1   0.81  
Kvitova            99.6     91.6   8.0   0.92  
Muguruza           98.1     82.5  15.6   0.84  
Pavlyuchenkova     97.9     84.5  13.4   0.86  
Sharapova          97.9     89.6   8.2   0.92  
Svitolina          97.6     78.2  19.4   0.80  
Stephens           96.1     75.1  21.0   0.78  
Halep              95.3     80.9  14.4   0.85  
Kerber             94.0     78.4  15.7   0.83

Oddly enough, having such a slow second serve doesn’t seem to be causing any problems. In today’s semi-final against Karolina Pliskova, Osaka won 81% of first serve points and only 41% of second serve points, but her typical performance behind her second serve is better than that. And in this match, both women feasted on the other’s weaker serves: Pliskova won only 32% of her own second serves. (Though to be fair, Pliskova had the second-largest gap of the players listed above. She tends to rely more on spin than speed when her first serve misses.)

Across her six matches, Osaka has won 73.3% of her first serve points and 49.7% of her second serve points–a bit better than the average quarter-finalist in the former category, a very small amount worse than her peers in the latter. The ratio of those two numbers–68%–is almost identical to those of Danielle Collins, Petra Kvitova, Anastasia Pavlyuchenkova, and Serena Williams, all of whom have smaller gaps between their first and second serve speeds. Of the eight quarter-finalists, Kvitova has the smallest speed gap of all, yet the end result is the same as Osaka’s, she’s just a few percentage points better on both offerings.

Here are the first- and second-serve points won in Melbourne for the eight quarter-finalists, along with the ratio of those two figures and each player’s serve-speed ratio from the previous table:

QFist           1SPW%  2SPW%  W% Ratio  Speed Ratio  
Kvitova         77.9%  52.8%      0.68         0.92  
Williams        74.7%  50.0%      0.67         0.85  
Osaka           73.3%  49.7%      0.68         0.74  
Collins         72.5%  50.0%      0.69         0.81  
Barty           70.8%  55.7%      0.79         0.87  
Pliskova        70.5%  50.0%      0.71         0.79  
Pavlyuchenkova  67.0%  44.9%      0.67         0.86  
Svitolina       66.5%  48.1%      0.72         0.80

Clearly, there’s more than one way to crack the final eight. With Kvitova, we have a server who racks up cheap points with angles instead of speed, rendering the miles-per-hour comparison a bit irrelevant. Serena’s results are close to Osaka’s, though she gets there with bit more bite on her second serves. And then there’s Svitolina, who doesn’t serve very hard or that effectively but can beat you in other ways.

Knowing all this, should Osaka hit harder second serves? In extreme cases, like today’s 81%/41% performance against Pliskova, the answer is yes–had she simply hit nothing but first serves and succeeded at the same rate, she would’ve piled up a lot of double faults but won more total points. But the margins are usually slimmer, and as we’ve seen, her second-serve performance isn’t bad, it just might offer room for improvement. Every player is different, but faster is usually better.

A thorough analysis of that question may be possible with the available data, but it will have to wait for another day. In the meantime, Saturday’s final will offer us a glimpse of contrasting styles: Osaka’s powerful first offering and soft second ball, against Kvitova’s angles and placement on both serves. Both my forecast and the betting market see the title match as a close one–perhaps Osaka’s second serve will be the shot that makes the difference.

The Naomi Osaka First-Set Guarantee

Italian translation at settesei.it

Today in the Australian Open quarter-finals, Naomi Osaka recorded a routine victory, beating 6th seed Elina Svitolina 6-4 6-1. She’ll face Karolina Pliskova in tomorrow’s semi-final, and she has a chance to finish the tournament as the top-ranked player in the world.

(See the bottom of this post for updates.)

Osaka’s sprint to the finish line against Svitolina was what we’ve come to expect from the 21-year-old. The Eurosport commentators shared a remarkable stat: The last 59 times Osaka has won the first set, she has gone on to win the match. (On Eurosport during the match, they said 57, making today’s win 58, but I believe they left out a 2017 win by retirement against Heather Watson in which the first set was completed.) The last time she failed to convert a one-set advantage into a victory was the final match of her 2016 season, in Tianjin against Svetlana Kuznetsova.

Of course, winning the first set is a big advantage for anyone. If two players are evenly matched and there’s no momentum effect, the winner of the first set has a 75% chance of finishing the job. In the real world, the woman who takes the first set is usually the superior player, so her odds in the second and third sets are even better still. On the 2018 WTA tour, the player who claimed first set went on to win the match 81.5% of the time.

Even if Osaka’s theoretical odds of converting one-set advantages are even higher, 59 matches in a row is one heck of a feat. Only 15 women have an active streak of 10 or more consecutive first-set conversions, and a mere four hold a running streak of at least 20. In addition to Osaka, Aryna Sabalenka has converted 25 straight first-set victories, Qiang Wang has won 27 in a row, and Serena Williams is ready to pounce as soon as Osaka falters, with a current tally of 51. Serena’s string of consecutive conversions stretches over an even longer span, back to April 2016, in Miami. (Remember who came back to beat her? Svetlana Kuznetsova.)

It’s no surprise to see Serena showing up near the top of this list. After several years of looking up various tennis records and streaks, I’ve discovered a few general rules. First, if you think you’ve found a noteworthy recent achievement, Serena did it better. Second, if it involves brushing aside the tour’s rank and file, Steffi Graf was even better than Serena. And third, no matter how impressive Serena’s and Steffi’s feats, the all-time record will belong to either Chris Evert or Martina Navratilova.

The first-set-conversion streak no different. In addition to her current streak of 51 straight, Serena won 61 in a row in 2002-03. That’s two matches and three places above Osaka, but it’s only 37th on the all-time list. Graf converted first-set advantages for more than twice as long, tallying 126 in a row from 1989 to 1991. As impressive as that is, my third rule holds with a vengeance: Evert converted 220 in a row between 1978 and 1981 to earn top billing on this list. Navratilova comes in second, but with the consolation that she holds third place as well. Martina and Steffi are the only women with multiple triple-digit streaks.

Here are the longest first-set conversion streaks held by players in the top 40. Many of these women put together multiple streaks of 60 or more, and in those cases I’ve listed only their longest:

Rank  Player                   Matches     Span     Notes  
1     Chris Evert                  220  1978-81  + 3 more  
2     Martina Navratilova          172  1982-84  + 5 more  
4     Steffi Graf                  126  1989-91  + 3 more  
6     Monica Seles                 112  1991-93  + 1 more  
7     Mary Joe Fernandez           105  1989-91            
8     Pam Shriver                  105  1986-88            
9     Vera Zvonareva               103  2006-08            
12    Martina Hingis                86  1996-97            
14    Arantxa Sanchez Vicario       85  1992-93            
16    Victoria Azarenka             79  2011-13            
17    Maria Sharapova               77  2010-12  + 1 more  
19    Margaret Court                74  1969-77            
21    Venus Williams                73  1999-01            
22    Sue Barker                    70  1973-78            
23    Evonne Cawley                 69  1978-80  + 1 more  
24    Lindsay Davenport             67  1999-00  + 1 more  
25    Tracy Austin                  67  1979-80            
26    Virginia Wade                 66  1975-78            
28    Gabriela Sabatini             65  1990-91            
30    Andrea Jaeger                 64  1981-82            
33    Claudia Kohde Kilsch          63  1986-87            
34    Kerry Reid                    62  1969-77            
37    Serena Williams               61  2002-03            
39    Anna Chakvetadze              60  2006-07            
40    Naomi Osaka                   59  2017-19  (active)

* Unfortunately all of these numbers come with a huge caveat. My historical WTA database isn’t perfect. I know that there are Evert and Navratilova matches missing, along with a handful of later results. For records like this, a single missing match could mean that Evert really had two streaks of 110 each, or any number of other permutations that would render my all-time list incorrect. So please, take these records as unofficial, and maybe the WTA will query their own–presumably more complete–database to produce a better list.

This is good company for the reigning US Open champion, and it looks even better if we narrow our view to 21st-century players. Only five of the women ahead of her on the list are active, and four of those are winners of multiple majors–another club that the 21-year-old could join this week. Her semi-final opponent, Karolina Pliskova, executed her own history-making comeback against Serena today. But if Pliskova finds herself down a set to Osaka, even she may not be enough of an escape artist to fight back against the best front-runner in women’s tennis.

Update: Osaka finished off the 2019 Australian Open with two more first-set conversions. In both the semi-final against Pliskova and the final against Kvitova, she won the the first set and went on to win in three. Thus, her streak is up to 61 and she has matched Serena’s best.

Danielle Collins and Surprise Major Semi-finalists

Italian translation at settesei.it

With a three-set win today over Anastasia Pavlyuchenkova, Danielle Collins became the first woman into the 2019 Australian Open semi-finals. She was already the biggest surprise of the eight quarter-finalists. A week ago, most pundits (myself included) would’ve picked dozens of players more likely to find themselves in the final four.

Collins, a 25-year-old American, has doubled her grand slam match experience at a single tournament. She first made a name for herself as a stellar collegiate player, winning national titles in 2014 and 2016, which earned her wild cards into her first two majors. While she gave Simona Halep a scare by taking a set in their 2014 US Open encounter, no wins resulted from either of the wild cards. After her run to the Miami semi-finals last year, she earned her way into three more slams, but she drew seeds at all three and had to settle for first-round loser’s checks. All told, Collins’s experience at majors amounted to five main draws, five first-round losses, and a couple of wins in qualifying.

There’s simply no precedent for what she has done in Melbourne. She opened by narrowly upsetting 14th seed Julia Goerges, then won six sets in a row to knock out Sachia Vickery, 19th seed Caroline Garcia, and 2nd seed Angelique Kerber, needing barely one hour per match. Today’s contest took a bit longer, but the end result was the same: a 2-6 7-5 6-1 victory over Pavlyuchenkova, who was playing in her fifth major quarter-final.

A berth in a major semi-final with no previous grand slam match wins: that’s something worth a database query. Since 1980, only three other women have done the same: Monica Seles at the 1989 French Open, Jennifer Capriati at the 1990 French, and Alexandra Stevenson in 1999 at Wimbledon. Collins doesn’t exactly fit in with that trio: Seles and Capriati were playing their first majors, and neither had reached their 16th birthdays. Stevenson was 18 years old, playing only her third slam main draw. The closest comp for Collins is found in the men’s game, where 25-year-old Marco Cecchinato reached the semis at Roland Garros last year despite recording no wins in his previous attempts at majors.

Reaching the final four in one’s sixth slam isn’t as rare. 12 different women have done so, including Seles, Capriati, and Stevenson, along with Venus Williams and Eugenie Bouchard. But again, Collins’s time at the University of Virginia sets her apart from this group: all but one were teenagers, and the only other exception, Clarisa Fernandez, was 20 years old when she reached the 2002 Roland Garros semi-final. The least experienced 25-year-old semi-finalist was Fabiola Zuluaga, who made it to the 2004 Australian Open semis in her 17th major, with 22 match wins in her first 16 tries.

History offers few precedents for Collins. While male collegiates such as Kevin Anderson and John Isner have established themselves in the top ten and gone deep at majors, the women’s game has always skewed younger. Yes, the days of 15-year-old sensations like Capriati and Seles are behind us, but the most recent major title went to 20-year-old Naomi Osaka, and the same year that Collins won her first national title for Virginia, Bouchard–who is two months younger than the American–reached the Wimbledon final. The greatest success story in women’s collegiate tennis belongs to Lisa Raymond, who is best known for her exploits on the doubles court.

Perhaps Collins’s success will change that, much as Anderson–whose first major semi-final came at age 31, in his 34th slam–has shown that college can fit in the plans of a would-be ATP star. With 20% of the WTA top 100 in their thirties, there’s more for a late starter to look forward to than ever before. It’s unreasonable to expect that Collins will be a regular feature at the tail end of grand slams, but it’s possible she’ll outdo Raymond, who peaked at 15th in the singles rankings. Next time we see her in the second week of a major, we won’t be so surprised.

Frances Tiafoe’s Narrow Margins

Italian translation at settesei.it

Yesterday, Frances Tiafoe added another breakthrough to his young career with a fourth-round defeat of 20th seed Grigor Dimitrov at the Australian Open. The whole tournament has been a coming-out party for the just-turned 21 year old, as Tiafoe only got this far thanks to an even more impressive upset of 5th seed Kevin Anderson in the second round. The American will see his ranking climb into the top 30 for the first time, and his marketability as a potential superstar will soar even higher.

The role of the statistical analyst is often to stand athwart an exciting trend yelling “Stop!,” and I’m afraid that’s my role today. Yes, Tiafoe is a compelling young player with a lot of potential. Throughout 2018 he repeatedly demonstrated he could hang with the best players in the world, something he further solidified with the win over Anderson last week. But the Dimitrov win, life-changing as it may be, was a bit of a fluke.

In fact, yesterday’s match was–by a couple of simple metrics–less impressive than a lot of his 2018 losses, including a defeat at the hands of Dimitrov in Toronto last year. Across 337 points against the Bulgarian on Sunday, Tiafoe lost more than half of them, winning only 34.7% of his return points compared to Dimitrov’s 39.5%. The resulting Dominance Ratio (DR) for the match is 0.88, a mark that almost never results in victory. (DR is the ratio of return points won to opponent return points won: 1.0 means that the players performed equally, and higher is better.) On the ATP tour last year, more than 92% of winners recorded a DR of 1.0 or better, and 97.4% of winners–that’s 39 out of every 40–won enough points to amass a DR of 0.9.

As I’ve said, many of Tiafoe’s losses have seen him play better. Against Dimitrov in Toronto, his DR was 0.98; versus Anderson in Miami his DR was 0.99 in a straight-set defeat; and even in his routine, 6-4 6-4 loss to Joao Sousa in the Estoril final, his DR was almost as good as it was yesterday, at 0.87. In the range of close-but-outplayed matches–let’s say DRs from 0.85 to 0.99–Tiafoe won 4 of 18 last year, and all but one of the wins were closer than yesterday’s triumph.

The trick to winning a match while tallying fewer than half the total points and a lower rate of return points than your opponent is to play better in the big moments, like break points. The American certainly did that, converting 5 of 13 break opportunities while limiting Dimitrov to only 3 of 18. Execution in tiebreaks also helps, though it didn’t make a difference in yesterday’s upset, as the two men split a pair of breakers. To Tiafoe’s credit, he outplayed the Bulgarian when it mattered most. In that sense, he deserved the victory, no matter what the stats say.

But break point and tiebreak performance tends to even out. Just because the 21-year-old captured lightning in a bottle at a few key moments to win a high-profile match doesn’t mean he’ll be able to do it again. Just as there are almost no players who win tiebreaks any more often than their overall performance would suggest, players with excellent single-year break-point records quickly regress to the mean. It may not be correct to say that Tiafoe was lucky to win yesterday–he may well have kept his focus and maintained his level better than opponent did–but whatever made the difference, it’s not something with predictive power. Next week, next major, or next year, he isn’t any more likely than the next guy to post a DR of 0.88 and come out on top.

Still, I’m not here just to throw cold water on a young player’s prospects. For one thing, had a couple of break points gone the other way yesterday and Dimitrov gotten through, a fourth-result result would still represent an encouraging step forward for the American. His upset of Anderson sported a particularly impressive DR of 1.29–35.1% of return points won compared to Kevin’s 27.2%–which was better than all but ten of Anderson’s matches last year. (Three of those ten came at the hands of Novak Djokovic, and seven of the ten were against top ten players.)

Tiafoe is getting better, and there are plenty of signs that indicate he’s the brightest young star in American men’s tennis. He’s accomplished a lot of things in Melbourne, but outplaying Dimitrov isn’t one of them.

Podcast Episode 45: Australian Open Week One

Episode 45 of the Tennis Abstract Podcast, with Carl Bialik of the Thirty Love podcast, is our attempt to cover the entirety of seven days of grand slam tennis in a one-hour podcast. On the men’s side, we discuss Federer’s vulnerability to an early upset, what to think about Tiafoe and the young American resurgence in general, and some solid under-the-radar performances from Milos Raonic and Roberto Bautista Agut.

We then make some cautious predictions about the Simona-Serena fourth round match and consider whether we should be as excited about Ashleigh Barty as my Elo ratings are. We even talk a bit about doubles, though it’s mostly about why it’s hard to talk about doubles. But don’t worry–we’ll keep trying.

Thanks for listening!

(Note: this week’s episode is about 65 minutes long; in some browsers the audio player may display a different length. Sorry about that!)

Click to listen, subscribe on iTunes, or use our feed to get updates on your favorite podcast software.

The Happy Slam is the Speedy Slam

Italian translation at settesei.it

Two years ago, during the 2017 Australian Open, I offered a partial explanation of the many upsets at that year’s first major. Novak Djokovic, Andy Murray, Angelique Kerber, Simona Halep and many others had been ousted before the quarter-finals, all to players with a more aggressive, attacking style. It turned out that the courts that year were playing particularly fast–quicker than any of the other slams, including Wimbledon, as well as most hard-court tour stops.

In Melbourne this year, the courts are playing even faster.

Through three rounds of play, almost 90% of the tournament’s singles matches are in the books. Based on my surface-speed metric, which measures how many aces are struck at each tournament while controlling for the mix of servers and returners, the 2019 Australian Open can boast the quickest surface at the event since at least 2011*, and the second-fastest conditions of any major in that time span.

* Match stats, even simple ones such as service points and aces, are increasingly tough to come by for the women’s game before 2011.

The average of my surface-speed ratings for the men’s and women’s events at 2019’s first major is 1.28, meaning that there have been 28% more aces than expected, given the mix of servers and returners across the matches played so far. The notably fast 2017 event was 1.23, the fastest US Open of the last eight years was 1.14 (in 2015), and last year’s Wimbledon, played on the surface that is supposed to be fastest of all, was a mere 1.06.

Here are the top ten fastest slam surfaces from 2011 to the present:

Speed Rating Tournament      
1.31     2011 Wimbledon    
1.28     2019 Australian Open* 
1.27     2014 Wimbledon    
1.27     2016 Australian Open 
1.23     2017 Australian Open 
1.20     2015 Australian Open 
1.18     2015 Wimbledon    
1.17     2013 Wimbledon    
1.17     2012 Wimbledon    
1.15     2014 Australian Open

* through first three rounds

Last year’s Aussie Open was a bit of an outlier, but even still, it barely missed this list, coming in 12th at 1.12.

At least most players arrived prepared. The warm-up events in Brisbane and Auckland ranked among the fastest conditions since the beginning of last season: Brisbane rates at 1.29 while Auckland came in at a blink-and-you’ll-miss-it 1.35. Last year, only four events per tour were faster.

In theory, such a speedy surface should work to the advantage of big servers with aggressive games. At least so far, it hasn’t worked out that way. Unlike in 2017, Djokovic, Halep, and Kerber are still in the running, while Kevin Anderson was an early casualty. On the other hand, the court speed does jibe with some results, like Maria Sharapova’s third-round upset of defending champion Caroline Wozniacki.

If the conditions are to impact the result of the tournament, it will have to happen in matches yet to come. A slick surface tends to favor Roger Federer, even if Djokovic remains the popular pick to hoist the trophy next Sunday. More immediately, a fast surface doesn’t bode well for Halep’s chances in her fourth-round match against Serena Williams. Facing Serena is difficult enough without the conditions working against you, too.

Dayana Yastremska Hits Harder Than You

Italian translation at settesei.it

At the 2019 Australian Open, tennis balls have more to fear than ever before. Serena Williams is back and appears to be in top form, Maria Sharapova is playing well enough to oust defending champion Caroline Wozniacki, and Petra Kvitova has followed up her Sydney title with a stress-free jaunt through the first three rounds.

And then there are the youngsters. Hyper-aggressive 20-year-old Aryna Sabalenka crashed out in the third round against an even younger threat, Amanda Anisimova. But still in the draw, facing Serena on Saturday, is the hardest hitter of all, 18-year-old Ukrainian Dayana Yastremska. Watch a couple of Sabalenka matches, and you might wonder if we’ve reached the apex of aggression on the tennis court. Nope: Yastremska turns it up to 11.

When Lowell first introduced his aggression score metric a few years ago, Kvitova was the clear leader of the pack, the player who ended points–for good or ill–most frequently with the ball on her racket. Madison Keys wasn’t far behind, with Serena coming in third among the small group of players for which we had sufficient data. Since then, two things have changed: The Match Charting Project now has a lot more data on many more players, and a new generation of ball-bashers has threatened to make the rest of the tour look like weaklings in comparison.

The aggression score metric packs a lot of explanatory power in a simple calculation: It’s the number of point-ending shots (winners, unforced errors, or shots that induce a forced error from the opponent) divided by the number of shot opportunities. The resulting statistic ranges from about 10% at the lower extreme–Sara Errani’s career average is 11.6%–to 30%* at the top end. Individual matches can be even higher or lower, but no player with at least five charted matches sits outside of that range.

* Readers with a keen memory or a penchant for following links will notice that in Lowell’s orignial post, Kvitova’s aggregate score was 33% and Keys was also a tick above 30%. I’m not sure whether those were flukes that have since come back down with larger samples, or whether I’m using a slightly different formula. Either way, the ordering of players has remained consistent, and that’s the important thing.

Here are the top ten most aggressive WTA tour regulars of the 2010s before Sabalenka and Yastremska came along:

Rank  Player                      Agg 
1     Petra Kvitova             27.1%  
2     Julia Goerges             26.8%  
3     Serena Williams           26.8%  
4     Jelena Ostapenko          26.5%  
5     Camila Giorgi             26.0%  
6     Madison Keys              25.9%  
7     Coco Vandeweghe           25.9%  
8     Sabine Lisicki            25.6%  
9     Anastasia Pavlyuchenkova  24.0%  
10    Maria Sharapova           23.2%

All of these women rank among the top 15% of most aggressive players. They end points more frequently on their own racket than plenty of competitors we also consider aggressive, like Venus Williams (21.9%), Karolina Pliskova (21.6%), and Johanna Konta (22.3%). Ostapenko bridges the gap between the two generations; she wasn’t part of the discussion when aggression score was first introduced, though once she started winning matches, it was immediately clear that she’d challenge Kvitova at the top of this list.

Here’s the current top ten:

Rank  Player               Agg  
1     Dayana Yastremska  28.6%  
2     Aryna Sabalenka    27.6%  
3     Petra Kvitova      27.1%  
4     Julia Goerges      26.8%  
5     Serena Williams    26.8%  
6     Jelena Ostapenko   26.5%  
7     Viktoria Kuzmova   26.0%  
8     Camila Giorgi      26.0%  
9     Madison Keys       25.9%  
10    Coco Vandeweghe    25.9%

Yastremska, Sabalenka, and even Viktoria Kuzmova have elbowed their way into the top ten. Yastremska’s and Kuzmova’s places on this list might be a little premature, since their scores are based on only seven and nine matches, respectively. But Sabalenka’s pugnaciousness is well-documented: her Petra-topping score of 27.6% is an average across almost 30 matches.

Tennis tends to swing between extremes, with one generation developing skills to counteract the abilities of the previous one. It’s not yet clear whether the aggression of these young women will catapult them to the top–after all, Sabalenka won only five games today against Anisimova, whose aggression score is a more modestly high 23.0%. Perhaps as they gain experience, they’ll develop more well-rounded games and return Kvitova to her place at the top.

In the meantime, we have the privilege of watching some of the hardest hitters in WTA history battle it out. Tomorrow, Yastremska will contest her first third round at a major in a must-watch match against Serena. There will be fireworks, but it’s safe to say there won’t be much in the way of rallies.