Italian translation at settesei.it
It is shaping up to be a breakthrough season for 22-year-old Russian Daniil Medvedev. His Tokyo title two weeks ago was his first at the ATP 500 level and his third on the season, after earlier triumphs in Sydney and Winston-Salem. The run in Japan was a particularly notable step, since he knocked out three top-20 players along the way. He had only four top-20 victories in the entire season leading up to Tokyo, and two of those were against the slumping Jack Sock.
His ATP ranking is rising alongside his results. The Winston-Salem title moved him into the top 40, and the Tokyo trophy resulted in a leap to No. 22. After a first-round win in Shanghai last week, Medvedev crept to his current career-high of No. 21. With a couple of wins in Moscow this week, he could overtake Milos Raonic and reach the top 20.
The improvement on the ATP ranking table is nothing next to the Russian’s race to the top of the Elo list. Last Monday, with the Japanese title in the books, Medevdev rose to No. 8 on my men’s Elo ranking. Since then, he has dropped two places but remains in the top ten, ahead of Marin Cilic, Kevin Anderson, and a host of others who outrank him on the official ATP list.
Given the discrepancy, what do we believe? Is Medvedev inside the top 10 or outside the top 20? Is Elo a leading indicator–that is to say, an early-warning signal for future ATP ranking milestones–or a misleading one? Elo is designed to be forward-looking, tuned to forecast upcoming match outcomes and weighting wins and losses based on the quality of the opponent. The official rankings explicitly consider a year’s worth of results, with no adjustments for quality of competition. In theory, Elo should be the better of the two measures for predicting longer-term results, but that assumes the algorithm works well, and that it doesn’t overreact to short-term successes. Let’s take a look at past differences between the two systems and see what the future might hold for the 22-year-old.
Precedents
Since 1988, 102 men have debuted in the ATP top ten. A slightly larger number, 113, have shown up in the top ten of my Elo ratings. There’s a very substantial overlap between the two, with 94 names appearing in both categories. Thus, 8 players have reached the ATP top ten without clearing the Elo threshold, while 19 have rated a spot in the Elo top ten without convincing the ATP computer to agree.
Here are the eight ATP top-tenners whose Elos have never merited the same status:
Player ATP Top Ten Debut ATP Top Ten Weeks Jonas Svensson 19910325 5 Nicolas Massu 20040913 2 Radek Stepanek 20060710 12 Jurgen Melzer 20110131 14 Juan Monaco 20120723 8 Kevin Anderson 20151012 31 Pablo Carreno Busta 20170911 17 Lucas Pouille 20180319 1
A few of these players could still make progress on the Elo list, especially Kevin Anderson, who is currently 11th, a miniscule five points behind Medvedev.
Here is the longer list of Elo top-ten players without any weeks in the official top ten:
Player Elo Top Ten Debut Elo Top Ten Weeks Carl Uwe Steeb 1989/05/22 3 Andrei Cherkasov 1990/12/11 1 Goran Prpic 1991/05/20 1 David Wheaton 1991/07/08 9 Jerome Golmard 1999/05/03 2 Dominik Hrbaty 2001/01/15 2 Jan Michael Gambill 2001/04/06 6 Nicolas Escude 2002/02/25 4 Younes El Aynaoui 2002/05/20 2 Paul Henri Mathieu 2002/10/14 8 Player Elo Top Ten Debut Elo Top Ten Weeks Agustin Calleri 2003/05/19 2 Taylor Dent 2003/10/06 10 Andrei Pavel 2004/05/10 2 Robby Ginepri 2005/10/24 1 Ivo Karlovic 2007/11/12 3 Roberto Bautista Agut 2016/02/22 1 Nick Kyrgios 2016/03/04 62 Stefanos Tsitsipas 2018/08/13 3 Daniil Medvedev 2018/10/08 2
* I define ‘weeks’ a little differently for Elo ratings, as ratings are generated only for those weeks with an ATP-level tournament or Davis Cup tie.
Most of these guys came very close to cracking the ATP top ten. For example, David Wheaton’s peak ranking was No. 12. With the exception of Nick Kyrgios, no one spent more than ten weeks in the Elo top ten without eventually reaching the same standard according to the ATP formula. This list shows that it’s possible to have a brief peak that cracks the Elo top ten but doesn’t last long enough to reflect the kind of success that the official ranking system was designed to reward. About one in six players with a top-ten Elo rating never reached the ATP top ten, though as we can see, the odds of remaining an Elo-only star fall quickly with each additional week in the top ten.
Kyrgios is a perfect example of the differences between the two approaches to player ranking. The Australian has recorded a number of high-profile upsets, which are the fastest way to climb the Elo list. But knocking out the second-ranked player in the world, as Kyrgios did to Novak Djokovic at Indian Wells last year, doesn’t have much impact on the ATP ranking when it happens in the fourth round. Usually, a player who can oust the elites will start piling up wins in a form that the official computer will appreciate. But Kyrgios, unlike just about every player in history with his talent, hasn’t done that.
In short, Elo will always elevate a few players to top-ten status even if they’ll never deserve the same treatment from the ATP formula. It’s too early to say whether Medvedev fits that mold. But where Elo really excels is identifying top players before the ATP computer does. Of the 94 cases since 1988 in which a man debuted in both top tens, Elo was first to anoint the player a top-tenner in 76 of them–better than 80%. The official rankings were first 10 times, and the two systems tied in the other eight instances. On average, players reached the Elo top ten about 32 weeks before the ATP top ten.
Here are the 11 most extreme gaps in which Elo got there first, along with the top-ten debuts of the Big Four:
Player ATP Debut Elo Debut Week Diff
Mariano Puerta 2005/07/25 2000/06/12 267
Marc Rosset 1995/07/10 1990/11/05 244
Fernando Gonzalez 2006/04/24 2002/10/07 185
Guillermo Canas 2005/05/09 2002/08/05 144
Mikhail Youzhny 2007/08/13 2004/11/15 143
Gaston Gaudio 2004/06/07 2002/04/29 110
Richard Gasquet 2007/07/09 2005/06/20 107
Tomas Berdych 2006/10/23 2004/10/11 106
Robin Soderling 2009/10/19 2007/10/08 106
Mark Philippoussis 1999/03/29 1997/03/24 105
Jack Sock 2017/11/06 2016/01/18 94
Player ATP Debut Elo Debut Week Diff
Roger Federer 2002/05/20 2001/02/19 65
Andy Murray 2007/04/16 2006/08/21 34
Novak Djokovic 2007/03/19 2006/07/31 33
Rafael Nadal 2005/04/25 2005/02/21 9
And in case you’re curious, the ten cases in which the ATP computer beat Elo to the punch:
Player ATP Debut Elo Debut Week Diff Stan Wawrinka 2008/05/12 2010/10/25 128 David Ferrer 2006/01/30 2007/05/28 69 Janko Tipsarevic 2011/11/14 2012/05/13 26 Rainer Schuettler 2003/06/09 2003/08/25 11 Tommy Robredo 2006/05/08 2006/07/24 11 Fernando Verdasco 2009/02/02 2009/04/06 9 Albert Costa 1997/04/21 1997/05/26 5 Nicolas Almagro 2011/04/25 2011/05/22 4 John Isner 2012/03/19 2012/04/15 4 Jiri Novak 2002/10/14 2002/10/21 1
The 32-week average difference is suggestive. As I’ve noted, Elo ratings are optimized to forecast the near future, so at least in theory, they reflect each player’s level right now. The ATP algorithm tallies each man’s performance over 52 weeks, with equal weight given to the first and last weeks in that timeframe. Setting aside improvement and decline due to age, that means the ATP computer is telling us how each player was performing, on average, 26 weeks ago. If Medvedev continues to oust top-20 players on a regular basis and claims another 500-level title or two, he could well be 26 or 32 weeks away from a top-ten debut.
Elo isn’t designed to make long-term forecasts–the tools needed to do so, for the most part, have yet to be invented. And the system occasionally gives high ratings to players who don’t sustain them for very long. But in general, a superlative Elo rating is a sign that a similar mark on the ATP ranking list isn’t far behind. So far, Kyrgios has managed to defy the odds, but the smart money still points to an eventual ATP top-ten debut for Medvedev.