I’ve just revised my published Elo ratings (men, women) to better reflect the performance of players who mostly compete at the (men’s) ATP Challenger and (women’s) ITF levels. Previously, my Elo ratings used only tour-level main-draw matches. For top players, it makes very little difference–not only do Novak Djokovic and Simona Halep play no matches at the lower levels, they rarely encounter opponents who spend much time there. But for the second tier of players, the effect can be substantial.
The Elo system rates players according to the quality of their opponents. Beat a good player with a high rating, and your own rating will jump by a healthy margin. Beat a weakling, and your rating will inch up a tiny bit. Essentially, Elo looks at each result and asks, “Based on this new result, how much do we need to adjust our earlier rating?” When Bianca Andreescu upset Caroline Wozniacki in Auckland last week, the system responded by upping Andreescu’s rating by quite a bit, and by penalizing Wozniacki more than for the typical loss. After a more predictable result, like Djokovic’s defeat of Damir Dzumhur, ratings barely move.
It’s important to understand the basic mechanics of the system, but the main takeaway for most fans is that Elo just works. The algorithm generates more accurate player ratings (and resulting match forecasts) than the official ATP and WTA rankings, among other attempts to rank players. Now, you can see Elo rankings for a much wider range of players.
Of of my main uses of Elo ratings is identifying players whose official rankings haven’t caught up to reality. For instance, a few months ago I noted when Daniil Medvedev moved into the Elo top ten, even though he has yet to crack that threshold on the official list. Most players who reach the top ten on the Elo table eventually do the same in the ATP or WTA rankings. Another two current examples are Aryna Sabalenka and Ashleigh Barty, considered by Elo to be two of the top three women on tour right now, even though neither is in the top ten of the WTA rankings. That may be too aggressive, and the margins at the top of the women’s list are tiny right now, but it is a clear signal that these women’s results bear watching. (We talked about this on the most recent Tennis Abstract podcast.)
Now that we have unified Elo lists that cover more players, let’s dig deeper. For each tour, let’s find the players current outside the official top 100s who are rated the highest by the more sophisticated formula. First, the ATP:
Player ATP Rank Elo Rank David Ferrer 124 36 Thanasi Kokkinakis 145 62 Miomir Kecmanovic 126 66 Jack Sock 105 77 Reilly Opelka 102 84 Ricardas Berankis 107 86 Marcos Baghdatis 122 87 Gilles Muller 137 88 Daniel Evans 190 89 Viktor Troicki 201 90 Horacio Zeballos 182 92 Jared Donaldson 115 94 Mikael Ymer 196 95 Egor Gerasimov 157 100 Lloyd Harris 119 102 Tommy Paul 195 104 Guillermo Garcia Lopez 101 106 Felix Auger Aliassime 106 108 Alexei Popyrin 149 109 Dudi Sela 240 114
One thing that pops out from the list is the number of veterans. Elo ratings are “stickier” than ATP rankings, since the official system works with only 52 weeks worth of results. Elo ratings make constant adjustments, but quality performances–even when they are more than 52 weeks old–continue to affect current ratings for some time. David Ferrer has had a hard time staying healthy enough to compete at his former level, but according to Elo, he remains fairly dangerous when he is able to take the court.
Fortunately the list isn’t all veterans. Elo suggests that younger players such as Thanasi Kokkinakis, Miomir Kecmanovic, Mikael Ymer, and Tommy Paul are better than their current rankings indicate.
The WTA list is even more laden with veterans, players who are still competing at a high level, if not as frequently as they used to:
Player WTA Rank Elo Rank Lucie Safarova 105 39 Coco Vandeweghe 100 40 Shuai Peng 129 43 Svetlana Kuznetsova 106 50 Sara Errani 114 52 Varvara Lepchenko 134 80 Laura Siegemund 110 84 Kristyna Pliskova 101 96 Anna Kalinskaya 167 97 Viktorija Golubic 104 98 Ivana Jorovic 117 99 Marie Bouzkova 120 103 Kateryna Bondarenko 140 104 Sachia Vickery 123 105 Veronika Kudermetova 111 107 Sabine Lisicki 198 109 Vitalia Diatchenko 131 112 Yanina Wickmayer 126 113 Nao Hibino 115 114 Danielle Lao 169 115
Part of the reason why so few prospects appear on this list is because of my decision to exclude ITF $25Ks. For example, up-and-coming 18-year-old Kaja Juvan, who knocked out Yanina Wickmayer in Australian Open qualifying today, hasn’t played nearly enough matches at higher levels to appear on my Elo list. But last year, she was 29-7 at ITF $25Ks, and won her last ten matches at that level.
Another issue is that the most promising women tend to climb into the top 100 more quickly. Another 18-year-old, Dayana Yastremska, rocketed up the rankings with a tour-level title in Hong Kong last fall. She sits at No. 59 on the WTA table, but after 13 top-100 wins in 2018, Elo is even more optimistic, placing her at No. 27, just ahead of Maria Sharapova and Venus Williams.
I’ll continue to update these expanded Elo ratings weekly and use them to generate forecasts for every tour-level and Challenger event. Enjoy!