Among the many good things that have happened to Flavia Pennetta and Roberta Vinci after reaching the final of this year’s US Open, both enjoyed huge leaps in Monday’s official WTA rankings. Pennetta rose from 26th to 8th, and Vinci jumped from 43rd to 19th.
Such large changes in rankings are always a little suspicious and expose the weakness of systems that award points based on round achieved. A lucky draw or one incredible outlier of a match doesn’t mean that a player is suddenly massively better than she was a couple of weeks ago.
To put it another way: As they are, the official rankings do a decent job of representing how a player has performed. What they don’t do so well is represent how well someone is playing, or the closely related issue of how well she will play.
For that, we can turn to Elo ratings, which Carl Bialik and Benjamin Morris used at the beginning of the US Open to compare Serena Williams to other all-time greats . Elo awards points based on opponent quality, not the importance of the tournament or round. As such, the system provides a better estimate of the current skill level of each player than the official rankings do.
Sure enough, Elo agrees with my hypothesis, that Pennetta didn’t suddenly become the 8th best player in the world. Instead, she rose to 17th, just behind Garbine Muguruza (another Slam finalist overestimated by the rankings) and ahead of Elina Svitolina. Vinci didn’t really return to the top 20, either: Elo places her 34th, between Camila Giorgi and Barbora Strycova.
While her official ranking of 8th is Pennetta’s career high, Elo disagrees again. The system claims that Pennetta peaked during the US Open six years ago, after a strong summer that involved semifinal-or-better showings in four straight tournaments, plus a fourth-round win over Vera Zvonareva in New York. She’s more than 100 points below that career-high level, equivalent to the present gap between her and 7th-Elo-rated Angelique Kerber.
The current Elo rankings hold plenty of surprises like this, having little in common with the official rankings:
Rank Player Elo 1 Serena Williams 2460 2 Maria Sharapova 2298 3 Victoria Azarenka 2221 4 Simona Halep 2204 5 Petra Kvitova 2174 6 Belinda Bencic 2144 7 Angelique Kerber 2130 8 Venus Williams 2126 9 Caroline Wozniacki 2095 10 Lucie Safarova 2084 Rank Player Elo 11 Ana Ivanovic 2078 12 Carla Suarez Navarro 2062 13 Agnieszka Radwanska 2054 14 Timea Bacsinszky 2041 15 Sloane Stephens 2031 16 Garbine Muguruza 2031 17 Flavia Pennetta 2030 18 Elina Svitolina 2023 19 Madison Keys 2019 20 Jelena Jankovic 2016
While Victoria Azarenka is still nearly 200 points shy of her peak, Elo gives her credit for the extremely tough draws that have met her return from injury. Another player rated much higher here than in the WTA rankings is Belinda Bencic, whose defeat of Serena launched her into the top ten.
The oldest final
Pennetta and Vinci are both unusually old for Slam finalists, not to mention players who reached that milestone for the first time. Elo doesn’t consider them among the very best players active today, but next to other 32- and 33-year-olds in WTA history, they compare very well indeed.
Among players 33 or older, Pennetta’s current rating is sixth best in the last thirty-plus years . As the all-time list shows, that puts her in extraordinarily good company:
Rank Player Age Elo 1 Martina Navratilova 33.4 2527 2 Serena Williams 33.9 2480 3 Chris Evert 33.4 2412 4 Venus Williams 33.3 2175 5 Nathalie Tauziat 33.9 2088 6 Flavia Pennetta 33.5 2030 7 Wendy Turnbull 33.1 2018 8 Conchita Martinez 33.3 2014
In the 32-and-over category, Vinci stands out as well. Her lower rating, combined with the somewhat larger pool of players who remained competitive to that ago, means that she holds 24th place in this age group. For a player who has never cracked the top ten, 24th of all time is an impressive accomplishment.
Keep an eye out for more Elo-based analysis here. Soon, I’ll be able to post and update Elo ratings on Tennis Abstract and, once a few more kinks are worked out, use them to improve the WTA tournament forecasts on the site as well.
- My numbers don’t precisely match those from the FiveThirtyEight article, but they’re close. The code I used is closely adapted from this, and all of us are working from the same dataset.
- A simple Elo rating doesn’t penalize players for missing lots of time, or even retiring, so a player who returns after many years away from tour comes back with the same ranking they had when they left. So technically, Martina Hingis (in her Fed Cup singles comeback this year) and Kimiko Date-Krumm (at the beginning of her 2008 comeback) belong on this list, making Pennetta 8th. However, that doesn’t seem to be in the spirit of the ratings, so I’ve left them out. Also, I only have player ages back to the early 1980s, which probably leaves out some greats who excelled past 30 in the 1970s.