The World’s Best Men’s Doubles Player Is American. Too Bad He Doesn’t Want To Play Doubles

At the World Tour Finals of men’s tennis in London this week, eight of the world’s best doubles teams are vying for the one of the most prestigious titles of the season. Bob and Mike Bryan, the 16-time Grand Slam winners, are competing with other elite duos such as U.S. Open winners Jamie Murray and Bruno Soares and Wimbledon champions Pierre-Hugues Herbert and Nicolas Mahut.

But the field is missing one notable name: Jack Sock, the American who won two doubles medals at the Olympics over the summer in Rio. Sock’s current doubles ranking of No. 14, reached by playing with seven different partners this year, places him ahead of four players present this week in London. But Sock didn’t make the cut because inclusion in the London field is based on ranking points accumulated by teams, not individual players, and each of his short-term teams finished far out of contention.

Yet it’s likely that the official rankings drastically undervalue Sock’s doubles prowess. According to a version of Elo¹ I created specifically for doubles tennis, his current level of play in doubles matches rates as the best in the world and one of the highest achieved by anyone in recent years. In addition to his men’s doubles bronze medal in Rio, Sock has won two titles in the past month, including an incredible run at the Shanghai Masters in which he and partner John Isner defeated four London-bound teams in succession.

Doubles Elo (D-Lo, if you will) is almost as straightforward as the singles system. The rating of any partnership is estimated as the average rating of the two players. (While there is anecdotal evidence that suggests a team improves as partners play together more often, incorporating that into the algorithm doesn’t make it any more accurate.) After every match, each of the four players’ ratings is updated by adding or dropping points based on the result and their opponents’ strength. I’m using D-Lo to forecast the doubles tournament at the World Tour Finals.

Sock is missing from the London field largely by choice. In July, he said he would compete in fewer doubles events in order to better focus on his singles career — he ranks No. 23 in singles, near his career high. He ended his partnership with Vasek Pospisil, the Canadian with whom he won the 2014 Wimbledon title, and skipped the doubles event at this year’s U.S. Open. Since September, he has played four events with four different partners — hardly the behavior of a would-be elite doubles player.

The American is hardly alone in his decision to prioritize singles. Doubles players perform far out of the spotlight, rarely netting the press and prestige of their singles-playing counterparts. What’s more, the top doubles players each earn about one-tenth the prize money that top singles players make. Plenty of elite singles players are accomplished on the doubles court — Roger Federer and Rafael Nadal both won Olympics doubles gold medals — but most usually elect to rest rather than play doubles for a lesser prize pool and a smaller fraction of the acclaim. Of the 16 doubles players in London, only Feliciano Lopez and Max Mirnyi have ever numbered among the top 20 on the singles ranking table, and for 39-year-old Mirnyi, that was 13 years ago.

Despite his priorities, Sock would have been a force to reckon with in London. A pairing with Pospisil would, as measured by Elo, outrank every team except for Herbert-Mahut and the Bryans. Even a partnership with Steve Johnson — Sock’s fellow bronze medalist and a lowly 56th on the Elo ranking table² — would be the fifth-rated team at the finals.

If he remains focused on singles and resists sticking with a steady doubles partner, Sock could still be a factor in future editions of the season-ending doubles event. The average age of the doubles participants in London this year is 33, while Sock is 24. According to Elo, the Bryans didn’t reach their peak until close to their 30th birthdays, and Mahut, at age 34, is having the best doubles season of his career. For most players, it would be a career-defining achievement to reach Sock’s current level of doubles skill. For the American, he has another decade to decide if it’s worth it.