Author: jsackmann

Ashleigh Barty’s Fully Baked Double Bagel

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, Feb. 9: A Perfect Opener for 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, Feb. 8: Andreescu and Kyrgios Post Strong Day 1 Results

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.

You can subscribe on iTunes, Spotify, Stitcher, and elsewhere in the podcast universe.

This is very much still an experiment, so please let me know what you think.

Serena’s 23 vs Margaret’s 24

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.

Expected Points, Feb. 7: Time to Embrace the Russian Future

Expected Points, my new short, daily podcast, highlights three numbers to illustrate stats, trends, and interesting trivia around the sport.

Daniil Medvedev and Andrey Rublev place Team Russia at the top of the international heap, Felix Auger Aliassime’s final-round struggles continue, and Serena Williams chases a record that, adjusted for common sense, she has already passed.

You can subscribe on iTunes, Spotify, Stitcher, and elsewhere in the podcast universe.

This is very much still an experiment, so please let me know what you think.

Everybody’s a Tricky Lefty

Tennis players like routine, so maybe that’s what makes left-handed opponents “tricky.” The phrase “tricky lefty” is so common as to be a cliché, leading me to ask on Twitter last night whether there’s such a thing as a lefty who aren’t described as tricky.

A few of you responded, suggesting names such as Petra Kvitova and Rafael Nadal. It’s true, great left-handed players win matches because they’re great, not because they’re unusual. Plenty of adjectives come to mind for Petra and Rafa before “tricky.” Tour coach Marc Lucero suggested a broader framework:

I suspect Marc is right, and he would know better than I would. It doesn’t make sense that all lefties are tricky, even if players don’t face them very often.

Let’s be pedantic and go back to my original question, though: Are there any lefties who aren’t described as tricky? Mihaela Buzarnescu is certainly no Kvitova, but she is more aggressive than the average WTAer, at least according to Match Charting Project stats. To answer this question, I did some hardcore 21st-century research and googled it.

More specifically, I googled the following:

“tricky lefty” tennis

That’s not a perfect filter, because it excludes things like “tricky left-hander,” “a lefty whose tricky game…” and so on. But it gives us a good overview. Skipping over results with instructional content (“how to handle a tricky lefty serve!”) and pages discussing amateur players, here are the first 27 players Google told me are tricky lefties:

Alas, the world’s content writers do not hold to Lucero’s logically consistent definition. While some of the examples that Google gave me come from blogs, which we might not expect to maintain high editorial standards (pot, kettle, etc), one of the mentions of Nadal’s trickiness came from a very respectable publication, written by a pundit whose name you would know. Many of the other players were described as tricky on the tour websites, or in direct quotes from players. (Caroline Wozniacki used the t-word for Buzarnescu.)

Are lefties tricky?

As I said at the outset, tennis players like routine. Unless you’ve reached the finals at Roland Garros, facing a lefty is out of the ordinary. It’s the same type of unusual as drawing an opponent with a monster serve (Ivo Karlovic is incessantly deemed “tricky”) or a finely-honed backhand slice. There’s a whole range of tired tennis tropes for the underspinners–they “slice and dice” (really? they chop up the tennis balls into small cubes?), and their trickiness is rivaled only by how “crafty” they are.

We can’t quantify this unless we reframe the question. If lefties are tricky–or, let’s say, they have more capacity to be tricky than right-handers do–it’s roughly equivalent to saying that left-handers have an advantage. And if southpaws have an edge, we’d expect to see more of them in high-level tennis than in the population as a whole.

Is there a disproportionate number of lefties? This was one of the first tennis analytics questions I tried to answer, almost exactly a decade ago, and my conclusion then was: not really.

In February 2011, 12 of the top 100 players in the ATP rankings were left-handed. That includes Nadal, who complicates things a bit, as he’s a natural righty. 10% of the population is left-handed, so 11 natural-born lefties out of 100 players is awfully close to what we’d expect if there was no advantage.

Don’t read too much into this, but things have changed a bit! At the moment, 15 of the top 100 ATPers are left-handed. (Still including Rafa, of course.) There’s only about a 4% chance that there would be so many lefties purely due to chance, or 7% if you class Rafa with the natural-born righties. It’s hardly a statistical slam dunk, and the case gets weaker when we broaden our view. There are 12 lefties among the next hundred male players, and only 18 lefties–fewer than we’d expect from chance alone–in the WTA top 200.

Paradoxically, the more lefty regulars on tour, the less uncomfortable they are to face. Put another way, the trickier they are, the less tricky they are.

There may well be an advantage to left-handedness, and its inherent trickery, in the junior or amateur ranks. (There is certainly an advantage when facing me!) But the evidence is flimsy that it extends to the highest level of the game. The real trick would be convincing everyone to start using a different adjective or–gasp!–treating non-superstar lefties as individuals with games that aren’t interchangeable, even if they do all use the same dominant hand.

Expected Points, Feb. 6: Garbine Muguruza Destroys the Field

Expected Points, my new short, daily podcast, highlights three numbers to illustrate stats, trends, and interesting trivia around the sport.

Garbine Muguruza posts her fourth consecutive easy victory, Felix Auger Aliassime is hitting untouchable first serves, and Sofia Kenin will have to beat the odds to defend her Australian Open title.

You can subscribe on iTunes, Spotify, Stitcher, and elsewhere in the podcast universe.

This is very much still an experiment, so please let me know what you think.

Expected Points, Feb. 5: A Two-Match Day Leaves Karen Khachanov the Top Man Standing

Expected Points, my new short, daily podcast, highlights three numbers to illustrate stats, trends, and interesting trivia around the sport.

Some of the biggest names on the women’s tour advance via the just-instituted third-set match tiebreak, Khachanov will play Jannik Sinner in the only meeting between seeds in Saturday’s men’s semi-finals, and Tony Trabert leaves a legacy of excellent play and longtime service to the game.

You can subscribe on iTunes, Spotify, Stitcher (click the “subscribe” button in the player), and elsewhere in the podcast universe.

This is very much still an experiment, so please let me know what you think.

Expected Points, Feb. 4: A Bad Day For Positive Tests

Expected Points, my new short, daily podcast, highlights three numbers to illustrate stats, trends, and interesting trivia around the sport.

On today’s episode: Thursday’s action in Melbourne was canceled due to a positive coronavirus test, Dayana Yastremska won’t be returning to action anytime soon, and Benoit Paire gets back in the swing of things with an ignominious service game.

You can subscribe on Spotify or Stitcher (click the “subscribe” button in the player), and iTunes is coming soon.

This is very much still an experiment, so please let me know what you think.

New Mini-Podcast! Expected Points, Feb. 3

I’m trying something new: A short, daily(!?) podcast to keep you up to date with the tennis world. Patterned after the Numbers by Barron’s finance podcast, Expected Points highlights three numbers to illustrate stats, trends, and interesting trivia around the sport. Today’s pilot episode is under four minutes long, and I’ll aim to keep each installment around this length.

Joining me for the inaugural episode is Carl Bialik of the Thirty Love podcast. Given the short duration, this will probably be a solo podcast most of the time, but I look forward to including other voices as time and logistics permit.

Today’s episode features Carlos Alcaraz, superstars falling early in the women’s tournaments, and the imminent return of Roger Federer.

Expected Points isn’t yet on iTunes … or anywhere else, for that matter. It will be soon. In the meantime, you can listen right here using the player below:

Please let me know what you think–format, content, whatever. I’ve opened up comments on this post so you can respond, and you may also send comments my way on Twitter.

(Don’t worry, the long-form Tennis Abstract Podcast isn’t going anywhere–we’ll continue with our sporadic schedule throughout the year.)