In their third round match today at the Australian Open, Sara Errani and Su Wei Hsieh played 232 points. The fastest serve either one hit registered at 93 mph (149 kmh), Hsieh’s first serves averaged 85 mph, and Errani’s mean first serve speed was 75 mph. I use the word “mean” here as more than just a way to avoid saying “average” so many times.
The two veterans are crafty–dare I say tricky–players with an arsenal of weapons once the ball is in play. But the serve is mostly just a stumbling block to make the best of. Hsieh won 62 of her 115 return points, good for 54% of Errani’s serves. This is more impressive than it sounds–the Italian double faulted only four times today. It’s fairly common for a winner on the women’s tour to win more than half of her return points, but what makes this match so weird is that Errani did the same. She won 63 of her 117 return points, also a 54% clip.
About half of WTA losers fail to convert better than 50% of their service points. But only 2.4% of winners miss the mark. And there’s a huge gap between 50%–mediocre and survivable–and Hsieh’s 46%. A 46% rate of service points won translates to a 40% likelihood of holding. Coincidentally, that’s exactly what both players did, each hanging on to their service games in 6 of 15 tries.
I have the relevant stats for just under 25,000 tour-level, main draw women’s matches since 2010, and only about 80 winners–0.3%, or less than once per 300 contests–won service points at a lower clip than Hsieh did today.
** I say “about” because the stats I have from the early 2010s aren’t perfect. A match with 60% of return points won is a prime candidate to be a mistake. I checked these 80 for obvious errors, like matches with a small number of service breaks, but those numbers aren’t perfect either.
There’s no grand analytical insight to be gleaned from a match like this. It’s just a glorious oddity that reminds us how many different ways there are to win matches. (And to be honest, you only need to watch Hsieh for about 90 seconds to recognize that.) In that spirit, here’s some more trivia:
Since 2010, this is only the 12th Australian Open main draw match in which neither player won half of her service points.
The only AO match in which neither player won 46% of their service points was the 2018 third-rounder between Anett Kontaveit and Jelena Ostapenko. They both held about 45.5% of their points, and 68% of total games (17 of 25) were breaks.
There have been about 400 tour-level matches since 2010 in which neither player wins half of their service points. Before today, 21 of those involved Errani, and she won 17 of them.
The other players who have been involved in at least 12 such matches are Monica Niculescu (16), Alize Cornet (14), and Carla Suarez Navarro (13). Today was only Hsieh’s 5th appearance on the list.
Perhaps oddest of all, this the first time in four tries that Hsieh avoiding getting bageled by Errani. Last time they played, in Istanbul in 2017, the Italian won, 6-0 6-1, needing only 55 minutes and a total of 87 points. Errani was so on-form that day that she won a whopping 66% of her service points. Hsieh finally turned the tables, even if she still hasn’t figured out how to stop this dogged opponent from breaking her serve.
Expected Points, my new short, daily podcast, highlights three numbers to illustrate stats, trends, and interesting trivia around the sport.
On today’s show: The third seed ousts a home favorite with a glittering serving display, the bottom half of the women’s draw is more than half full of former slam champions, and Su-Wei Hsieh wins an upside-down match against Sara Errani.
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Bill, who dug into Match Charting Project data for his piece, explains how Djokovic tactically differs from the competition, how his game has changed over the years, and whether the nature of his game makes it tough to fully appreciate. I also encourage him to speculate about whether Novak will reach 20 slams, and if that would make him the greatest of all time.
Also on the agenda: whether tour-wide parity is better than dominance, how ESPN (and tennis media in general) could cover the sport differently, and why there are so few people who love both tennis and college football.
Thanks for listening!
(Note: this week’s episode is about 48 minutes long; in some browsers the audio player may display a different length. Sorry about that!
In case you haven’t heard, I’m now doing a short (~4 minutes) daily podcast called Expected Points. Here’s today’s episode.
The TAP book club will reconvene in a few weeks with our next selection, John Updike’s 1968 novel, Couples. Read along with us, share your thoughts, and suggest topics/questions/comments for our discussion in a future episode.
Expected Points, my new short, daily podcast, highlights three numbers to illustrate stats, trends, and interesting trivia around the sport.
On today’s show: Sofia Kenin’s Australian Open title defense ends at the hands of the Estonian upset master, Thanasi Kokkinakis offers four hours of evidence that he’s finally healthy, and Andy Murray toils 9,000 miles away at a Challenger in Italy.
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An underhand serve functions in two ways–one short term, one long term. The short-term goal is to win a single point. Your opponent is standing way back, and the service equivalent of a drop shot could go for a 50 mile-per-hour ace. The long-term goal is to give your opponent something to worry about, perhaps distracting him or changing his return position for games, or sets to come. It’s not about winning a single point, but about slightly improving your odds in many future points.
In his second-round match yesterday against Ugo Humbert at the Australian Open, Nick Kyrgios opted for both. He unleashed the underhander twice, once at 40-love in his second service game, and again at 5-5, 40-30 in the fourth set.
The first dropper was on as meaningless a point as he could ask for. Kyrgios’s probability of winning a service game from 40-love is about 99.6% (really!), so the risk of losing the game after throwing away a point is essentially nil. He won the point with a backhand winner on his next shot, but the object of the exercise–assuming there was a tactical one, and I’ll give Nick the benefit of the doubt here–was more long-term oriented.
He delivered the second underarm serve on a much higher-pressure point. Kyrgios is still heavily favored to hold serve from 40-30, but he could be forgiven for feeling some nerves and wishing for a free point. This time he netted the underhand attempt and ended up winning the point after a (conventional) second serve.
A drop of data
When the underhand serve first started to go mainstream a couple of years ago, I updated the Match Charting Project spreadsheet to allow us to track these attempts. Counting the Kyrgios-Humbert match, we’ve now gathered the results of 35 drop-serve attempts across 20 different men’s matches. (We’ve recorded many women’s underhand serves as well, but most of those belong to Sara Errani, who has a different set of goals when she goes that route.)
35 points is awfully far from big data, but it is enough to get a taste of how a handful of players are deploying this unorthodox weapon.
The most common point score for an underarm serve is 40-love. Of the 35 attempts, 40-love accounts for 12 of them. Another 4 occured at 40-15, plus two more at 30-love, so roughly half of the recorded drop serves came with a service game more or less secured. A few of the remaining points were also relatively unimportant ones, like Daniil Medvedev’s underhander at love-40 toward the end of a 2019 US Open match against Hugo Dellien, and Alexander Bublik’s back-to-back tries at 0-5 and 1-5 in a tiebreak against John Isner.
Bublik is the major source of unimportant-point underarm serving. He’s responsible for 19 of the recorded points, 16 of which were at 40-love, 40-15, 30-love, or those two tiebreak points I just mentioned.
Inferring tactics
Since so many underarm serves are deployed at low-pressure moments, it’s tempting to conclude that players are thinking long term.
On the other hand, our handful of recorded underhand deliveries–even the ones on 40-love points–don’t skew toward the beginning of matches. We have two charted matches in which Robin Haase tried an underhander: a 2019 Budapest tilt against Borna Coric in which he made his first attempt in the third game, and a 2020 Davis Cup rubber when he waited until the 32nd game of the match.
Poster boy Bublik is inconsistent on this as well. Twice he has brought out the underhander in his second service game–once in the Newport match versus Isner, and another time the same summer in Washington against Bradley Klahn. Yet at the US Open against Thomas Fabbiano the same year, he didn’t unleash the secret weapon until 40-love in the 32nd game of the match.
I’ll admit, it might be foolish to try to detect the grand plan underlying the behavior of Alexander Bublik.
But it works!
Yeah, our 35 points make up tiny sample, but… the server won 27 of these 35 points! That’s 77%, and it includes underarm first-serve attempts that missed. When players had to hit a conventional second serve, they still won 7 of 10 points–a rate of second serve points won that any player would happily accept.
These numbers–cautiously as we must treat them–suggest that the underarm serve trend has plenty of room to run. The rare players who dare to risk ridicule are still only using the drop serve less than twice per match, and of course the vast majority of men on tour are never hitting them at all. The more common the underhand delivery becomes, the less effective it will be, but there’s a lot of space between the current drop-serve win percentage of 77% and the typical player’s success rate on serve. Tour average is around 65%, and only the most dominant servers exceed 70%.
As Bublik and friends have discovered, there’s little risk in mixing things up. Strong servers like him and Kyrgios have plenty of low-leverage opportunities to remind their opponents that surprises could be in store later in the match, when the stakes are raised. Our very early indicators suggest that where Kyrgios has gone, the rest of the tour could profitably follow.
Expected Points, my new short, daily podcast, highlights three numbers to illustrate stats, trends, and interesting trivia around the sport.
On tap today: Serena takes two easy steps toward her 24th major title, Reilly Opelka fires another barrage of aces in a losing effort, and Barbora Krejcikova opens her pursuit of a first unmixed title in Australia.
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Not every double bagel is created equal. Today in Melbourne, Ashleigh Barty beat Danka Kovinic without losing a game, dropping only ten points. By contrast, a memorable Stuttgart first-rounder from 2015 saw Sabine Lisicki lose 6-0 6-0 to Zarina Diyas, requiring 88 points and well over an hour to play. Lisicki won 37.5% of total points played that day, while Kovinic snuck off with just 16.7%.
Barty’s performance was among the most dominant in recent WTA history. I have mostly complete match stats for the women’s tour going back to about 2010, and in that time frame, only two main draw double bagels have finished in fewer than 60 points:
Points Year Event Round Winner Loser
57 2017 Hua Hin R32 Golubic Wisitwarapron
59 2019 New Haven R32 Cepelova Small
60 2021 Aus Open R128 Barty Kovinic
60 2019 Madrid R16 Halep Kuzmova
61 2010 Estoril R32 Garrigues De Lattre
62 2017 Bol R32 Mrdeza Thombare
63 2013 Aus Open R64 Sharapova Doi
63 2015 Bastad R16 Barthel Zanevska
64 2015 Toronto R64 Vinci Knapp
64 2017 Tokyo R32 Krunic Date
64 2011 Luxembourg R32 Garrigues Kremer
64 2012 Copenhagen R32 Cornet Ejdesgaard
65 2010 Moscow R16 Kirilenko Bondarenko
Today’s drubbing is even a bit more impressive than it looks on that list. Barty lost only 10 points–among the matches listed above, that’s equal to Jana Cepelova, two more than Viktorija Golubic, and fewer than everyone else. Not all 60-pointers are identical: Because Kovinic forced one deuce game today, Barty had to win 50 points instead of the minimum 48. Simona Halep only needed 48 in her 2019 Madrid double bagel, meaning that she lost 12 of the 60 points played that day.
Double bagel probability
There’s a bit of luck involved in winning twelve games in a row, even for a player at the top of her game. Kovinic won 10 points today, so even if she did exactly the same thing in her next match, one can imagine her “bunching” her points differently and putting a game or two on the board. Unlikely, but possible.
For any match, we can take the winner’s rate of service points won and return points won, and then generate the probability that she wins twelve games in a row. I did this exact exercise last January during the ATP Cup when Roberto Bautista Agut handed a 6-0 6-0 loss to Aleksandre Metreveli. Metreveli lasted 97 points, or 61% longer than Kovinic. If Metreveli had continued to play at that level, his chances of losing twelve games in a row would have been a mere 14.8%.
Barty won 88.9% of her service points and 78.8% of her return points against Kovinic today. If she continued at those rates, assuming no unusual streakiness or significantly better or worse performance at certain point scores, she would hold serve 99.8% of the time and break in 97.2% of return games. (By contrast, Bautista Agut’s probabilities were “only” 98.9% and 73.6%.)
The likelihood of a 6-0 6-0 bagel is simply that of six holds and six breaks. For Barty: (99.8% ^ 6) * (97.2% ^ 6), or 83.6%. In other words, the way she was playing today, Ash would score the double bagel five out of six times.
This probability is the number that really tells you how dominant a player was, even if it’s a few levels more complex than counting points and points lost. And by this measure, only Golubic’s great day holds a place on the list ahead of Barty’s. The p(DB) column shows the probability of a double bagel.
p(DB) Year Event Round Winner Loser
88.7% 2017 Hua Hin R32 Golubic Wisitwarapron
83.6% 2021 Aus Open R128 Barty Kovinic
80.0% 2019 New Haven R32 Cepelova Small
76.8% 2019 Madrid R16 Halep Kuzmova
75.4% 2017 Tokyo R32 Krunic Date
68.8% 2011 Luxembourg R32 Garrigues Kremer
66.9% 2010 Estoril R32 Garrigues De Lattre
64.9% 2017 Bastad R32 Krejcikova Beck
64.1% 2017 Bol R32 Mrdeza Thombare
62.0% 2010 Moscow R16 Kirilenko Bondarenko
60.7% 2016 US Open R128 Suarez Navarro Pereira
59.2% 2013 Aus Open R64 Sharapova Doi
59.2% 2018 US Open R128 Gavrilova Sorribes Tormo
Gotta love the coincidence here. 13th on this list is a 2018 US Open first-rounder between Daria Gavrilova and Sara Sorribes Tormo. Both players are still going strong (except when Sorribes Tormo was up 6-0 4-0 on Aryna Sabalenka in Ostrava last October), both are in Melbourne, and they drew each other again this week. Gavrilova won again, though not quite as easily. Her reward? A second-round match on Thursday with Ashleigh Barty.
Expected Points, my new short, daily podcast, highlights three numbers to illustrate stats, trends, and interesting trivia around the sport.
The women’s top seed records a flawless start to the tournament, the experienced Feliciano Lopez withstands belated newcomer Li Tu, and Sloane Stephens finds a new way to lose.
You can subscribe on iTunes, Spotify, Stitcher, and elsewhere in the podcast universe.
The Expected Points podcast is still finding its feet, so please let me know what you think.
Expected Points, my new short, daily podcast, highlights three numbers to illustrate stats, trends, and interesting trivia around the sport.
Bianca Andreescu has a winning return after a 15-month layoff, Nick Kyrgios defies the odds with success on both sides of the ball, and almost everybody—even Bernard Tomic—gets through day one injury-free.
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This is very much still an experiment, so please let me know what you think.
Since 2017, Serena Williams has held 23 major titles, leaving her just one shy of Margaret Court’s 24. The Williams-Court comparison forces us to think across eras in the same way that Federer-vs-Laver does, with the additional complication that Court has earned herself extreme dislike among many fans and fellow champions.
Let’s set aside the off-court stuff and work this out. The pro-Court case is simple: 24 is greater than 23, and you have to evaluate players relative to their own eras. The pro-Serena side is equally straightforward: 11 of Court’s 24 titles came in Australia, before Melbourne was a mandatory tour stop. Regardless of the era, Court’s home event was weaker back then.
As much as possible, I’m going to try to hold to the “relative to their own era” assumption. Everyone seems to accept it when it comes to Laver-vs-Federer. Plus, if we drop that constraint, the whole exercise is meaningless. With improved technology, fitness, and coaching, of course today’s players are better. But that’s not what people are talking about when they pick a side of Serena-vs-Margaret or Rod-vs-Roger.
Attentive readers of this blog might recall I took a stab at this problem back in 2019. That attempt relied on some extreme approximating due to the lack of pre-Open Era women’s tennis data. Regular readers will also know that the state of pre-Open Era women’s tennis data has vastly improved in the last few months. Tennis Abstract, plus the associated GitHub repo, now contains thousands of match results back to the mid-1950s.
Adjusting Australia
Let’s be clear: I’m not about to settle whether Margaret Court or Serena Williams (or someone else) is the GOAT of women’s tennis. That debate depends on much more than grand slam titles.
Today’s question is: How do Williams’s 23 titles stack up against Court’s 24?
That boils down to an even simpler question: How do Court’s 11 Australian titles measure up against other slams, then and now?
The anecdotal evidence is strongly anti-Margaret. As I mentioned in this morning’s Expected Points, the 1960 Australian Championships–Court’s first major title–had a 32-player draw (strike one), and 30 of those players were Australian (strikes two and three). Yes, it was a strong era for Australian women’s tennis, especially a few years later, but the tournament was hardly a showcase of international superstars. As such, it isn’t what we think of as a “major” tournament these days.
I’ve done a lot of “slam adjustments,” mostly to track the difficulty of the majors won by Djokovic, Federer, and Nadal. (Here’s the most recent.) The basic approach is simple. For each tournament, take the winning player’s draw, and for each match, calculate the chance that an average slam winner on that surface would beat that set of opponents. (Odds are determined by my Elo ratings, which are based on results before the event.) Take the resulting probabilities–on average, around 14% between 1952 and 2020–and normalize them, so that a mid-range slam draw is 1.0. Tougher draws are higher than 1, and easier draws are lower.
Equalizing the eras
This type of adjustment gets us most of the way there, but it doesn’t directly confront the “relative to the era” issue. The field in general was more lopsided in the 1960s than it is now, with a handful of very strong players swatting away a pack of also-rans who struggled to win more than a game or two per set against the elites. That in itself is a point in favor of Serena (and modern players in general), but again, on the Laver-vs-Federer principle, that’s not what we’re talking about today.
The easiest way to express this idea that all eras are equivalent is to use as a standard each season’s Wimbledon, the one tournament that everybody always wanted to play, and almost everyone actually did play. To avoid year-to-year fluctuations based on short-term injuries, we’ll make things a bit more resilient and compare the strength of each year’s Australian draw to the average strength of that year’s Wimbledon and US draws.
For example, my slam adjustments consider 1960 to be a strong year. Maria Bueno’s Wimbledon title was 40% more difficult than the average slam draw, and Darlene Hard’s US victory was about 30% tougher than usual. Court’s Australian title that year comes out as exactly average, so we compare Australia’s 1.0 to the average of Wimbledon and the US ( (1.4 + 1.3) / 2 = 1.35), and the 1960 Australian title, relative to the era, measures as:
1 / 1.35 = 0.75
The mostly-Australian field wasn’t as weak as the caricature makes it out to be, but it was weaker than the marquee majors that year.
Here is how the strength of the Australian draw has evolved relative to the other grass- and hard-court slams from 1952 to the present:
Except for an outlier in 1965, when Bueno, Billie Jean King, and several other international stars turned up, the Australian Championships was a second class member of the grand slam club until around 1980. It’s had plenty of weak years since then, as well, partly because of players who skipped due to injury, and partly due to contenders losing early, giving the eventual winners easier paths.
The main event
Margaret Court won the Australian 11 times. By this measure of relative strength, those titles were worth 62% as much as the other majors in those years. The strenght of individual titles ranged from a low of 0.29 in 1961, when no international elites made the trip, to a high of 1.02 in 1965, when the field was positively star-studded.
Serena Williams has won the Australian seven times. It is tempting to leave that “7” as is, because Melbourne is now a mandatory tour stop and virtually every woman on tour considers it one of the top targets in her season. However, we should treat Serena’s seven the same way we adjusted Court’s 11. For all the era differences, some things remain the same, like jetlag and the difficulty of playing top-flight tennis only a few weeks into the season.
Williams’s seven were worth, on average, 88% as much as the other majors in their respective years. The weakest of the bunch was her last, in 2017. So many top players lost early that Serena never faced a top-eight opponent.
Court’s 11 titles, then, are equivalent to about 7 non-Australian majors–a penalty of four. Serena’s 7 are worth about 6 non-Australian majors–a penalty of one.
The final, adjusted tally: Williams 22, Court 20.
Margaret Court was one of the greatest players of all time, but her position the all-time grand slam singles list depends too much on the shifting status of her home event. When we properly account for the Australian tournament’s position for decade as the most minor major, Court loses her remaining claim to the top spot. Serena may yet win 24, but to match or exceed Court, she shouldn’t have to.
