by David Arkow
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If this year’s French Open proved anything, it was that women’s tennis is as competitive as ever. The average ranking of the eight female quarterfinalists was 33, compared to 10 for the men, with No. 33 (at the time) Barbora Krejcikova becoming the eventual winner at Roland Garros. The theme is expected to continue at Wimbledon. World No. 1 Ashleigh Barty retired in the second round of the French with a hip injury and has not played any warm-up tournaments since. Fan favorite Naomi Osaka has withdrawn to take “personal time with family and friends.” Defending 2019 champion Simona Halep, who also skipped Roland Garros, just pulled out of the draw with a calf injury. This all creates a prime opportunity for Serena Williams to potentially capture the elusive No. 24 Slam to tie Margaret Court’s Open Era record on her best surface. Despite the uncertainty surrounding the women’s draw, we attempted to predict a winner, simulating the tournament to find estimated probabilities for every single player in the draw to not only reach any given round but also to win it all.
Trying to predict outcomes with probabilities is common in sports. But it is much easier to do in a single game between two teams or even your standard 16-team playoff bracket than it is for a Grand Slam tennis tournament with a draw size of 128. This is because a lot of the probabilities are interdependent and can change meaningfully with each result, particularly unexpected ones. For example, if Barty were to lose in an earlier round in the draw, Serena’s probability of winning Wimbledon would go up drastically since she would no longer have to play her in the semis.
Nevertheless, we can still try to predict the outcome through a simulation. For mine, I used Tennis Abstract’s Elo ratings, which can be adjusted for different surfaces. For instance, Petra Kvitova is the seventh-best player overall by Elo, but when just looking at grass, the two-time Wimbledon champ rises to third. Now with the actual draw, we can simulate the tournament thousands of times using Elo ratings in order to see the different potential outcomes. This will ultimately give us a probability of each player making a certain round or even winning. For instance, if Serena wins the simulation 1,000 out of 10,000 times, she has an approximately 10% chance of winning. While there is seeding in tennis (No. 1-No. 32) the draw is more random than in other professional playoffs, which rely purely on seeding. In a Grand Slam, a No. 1 seed could play a No. 17 seed or a No. 32 seed in the third round.
In addition, grass courts, as opposed to hard and clay, likely have the most upsets as it is the most unfamiliar for the players. Especially this year with so few warm-up tournaments between the French and Wimbledon, players aren’t as fine-tuned for the sharp transition from the slowest to the fastest surface. Given that some players won’t have played on grass in more than two years―there was no grass court season in 2020 because of the pandemic―this year’s tournament could also greatly advantage certain playing styles (big servers, volleyers, slicers).
Ashleigh Barty: The current women’s No. 1 enters the draw as the statistical favorite with a 25% chance of taking the title, but this should be taken with great caution. Barty’s past two tournaments have both ended with her retiring. She pulled out of the Italian Open quarterfinals against Coco Gauff with an arm injury and then withdrew from the French Open with an unrelated hip injury, after dropping the first set to Magda Linette in the second round. Barty has chosen to avoid playing any grass court warm-up tournaments to give her body the most time to recover. Even though she’s played only 15% of her career matches on grass, she has a 76% career winning percentage, compared to 72% on hard and 68% on clay. Barty has one of the most effective slices on the women’s tour (a shot that is becoming much less common), which will serve her well on the low-bouncing grass. She also leads the WTA this year in aces (209). The shorter grass court rallies should benefit Barty’s lingering injuries. If Barty is able to remain healthy, she could look to capture her second Slam title as she’s been due for a while.
Serena Williams: Tied for her career best Slam, Wimbledon is the best shot that Serena has at tying Margaret Court’s Open Era record of 24 Slams, and the math bears that out. Her performance at Roland Garros was solid but still underwhelming to many fans who always expect her to make a deep run (the simulation only gave her a 0.5% chance to win in Paris). She has an 88% career winning percentage compared to 85% on hard and 82% on clay, all very impressive. Her flat, big-hitting ground strokes and fast serve suit the grass court game well. Serena dominates at holding her serve, winning 80% of her service games in her last full season in 2019 (good for second on tour). Since giving birth to her daughter in 2017, Williams has had the most success at Wimbledon, making the finals in both 2018 (lost to Angelique Kerber) and 2019 (lost to Simona Halep). While the simulation might be low on Serena’s chances due to her recent struggling performance, she might defy the odds.
Former Champions (Petra Kvitova and Angelique Kerber): Both Kvitova and Kerber have career grass court winning percentages that are almost 10% greater than their performance on hard courts. Kerber just won her home-country tournament in Bad Homburg, defeating Kvitova in a tight three-set semifinal. Kerber is slated for a potential third-round matchup and rematch of the 2018 final with Serena (of which she would have a 57% chance of winning). Kvitova and Kerber are the two most likely players to outperform their seeds, as they rank third and ninth in grass Elo, respectively.
Coco Gauff: Gauff is coming off her deepest Slam run of her career, making it to the quarterfinals of Roland Garros before losing to eventual champion Barbora Krejcikova. The 17-year-old burst onto the scene at Wimbledon in 2019, defeating Venus Williams on her memorable run to the fourth round as a qualifier. Since then, Gauff has steadily risen and currently ranks at a career high No. 23 on the WTA Tour. Incredibly, Gauff had only played four grass court matches in her career up until this year (all at that 2019 Wimbledon), so she doesn’t have much experience on the surface. Therefore, it is difficult to get a precise Elo rating given the small sample size, making her somewhat of a wildcard. She did suffer a second round exit at the warm-up tournament in Eastbourne, to Anastasija Sevastova (No. 61), but she also upset Elise Mertens (No. 16) in the first round. Nevertheless, Gauff enters the draw as the American with the highest chances (5% of winning it all).
Aryna Sabalenka: Sabalenka enters Wimbledon as the No. 2 seed, thanks to the absence of Osaka and Halep, but the Belarusian’s odds are far below that. As the 10th-ranked player by grass Elo, Sabalenka has a 3% chance of winning the title. She has won only 50% of her career matches on grass and lost in the first round of the last two Wimbledons. American fan favorite Madison Keys upset her in the first round of the Berlin tournament, and she just lost in the quarters in Eastbourne as the top seed.
Barbora Krejcikova: It’s hard to think that the most recent Slam champion might be overrated heading into Wimbledon. Krejcikova entered the French as No. 34 and is now seeded 14th at Wimbledon. She’s never made the main draw at Wimby before and has only won a single qualifying round. Interestingly, she did win the 2018 doubles title alongside Czech compatriot Katerina Siniakova (the pair are the No. 1 doubles team in the world), with whom she has also won two French Opens (2018 and 2021). Playing on grass has a very steep learning curve and one that favors veteran players more so than others. Krejcikova will likely continue some of her momentum from Paris into London and make her deepest Wimbledon run yet, but she has a mere 11% chance of making the second weekend.
Wimbledon is the most prestigious of the four Slams and often the most coveted by all the players. The uniqueness of grass makes for an exciting tournament with lots of intriguing stylistic matchups, big serves, explosive shots and surprising upsets. The women’s side brings the promise of a first-time winner and a potential young new star to emerge.
David Arkow ’24 is an economics major and member of the Harvard Varsity Men’s Tennis Team. He also serves on the board of HSAC. If you have any questions about this article, you can reach out to him @darkow.college.harvard.edu. Also check out his preview and predictions for the men’s side of the draw.