Unicorns of the WTA

With the US Open hard court swing just around the corner, Ash Barty heads into the last leg of the season with the highest rating in women’s singles and doubles. Such simultaneous dominance in singles and doubles has, in the past decade, only been matched by Serena Williams.

In only a matter of days, the 2019 men’s and women’s champions of Wimbledon will be determined, with either Simona Halep or Serena Williams on the women’s side and, most probably, one of the Big 3 on the men’s side taking the titles. While the 40th meeting of Federer and Nadal and the resurgence of Halep and Williams from their mid-season struggles are interesting storylines, I can’t help but feel some pangs for something utterly new to shake up the sport.

Ash Barty’s recent ascent to the World No. 1 and Coco Gauff’s breathtaking run at Wimbledon have been the best recent examples of tennis defying the ‘same old’. Can we expect the rest of the season to continue that trend?

Motivated by this question, I had a look at the latest standing in the hard court ratings, using my Elo Margin of Victory player ratings. (During the first week of Wimbledon, I was in Athens talking about this rating system as part of the Mathsport International conference, and, if your curious to know more about the technical details, slides from the talk will be available at the conference website soon.) For rating doubles, I rate a player as if they played two singles matches against each of their doubles' opponents, which is a bit awkward, I know, but I think it can still provide a reasonable measure of the relative strengths based on doubles play alone.

Below is the list of top 10 women’s singles and doubles players that query turned up. Does anything stand out?

Current Hard Court Ranking Player Singles Rating Player Doubles Rating
1 Ashleigh Barty 2369 Ashleigh Barty 2244
2 Serena Williams 2320 Coco Vandeweghe 2180
3 Karolina Pliskova 2307 Barbora Strycova 2176
4 Petra Kvitova 2298 Andrea Hlavackova 2169
5 Simona Halep 2293 Kristina Mladenovic 2166
6 Johanna Konta 2223 Venus Williams 2153
7 Angelique Kerber 2192 Victoria Azarenka 2150
8 Kiki Bertens 2191 Timea Babos 2144
9 Elina Svitolina 2185 Elise Mertens 2139
10 Naomi Osaka 2176 Su-Wei Hsieh 2136

What jumped out to me was seeing Barty get the highest singles and doubles rating. I thought, surely, with so many years of the best singles players competing almost exclusively in singles, this must be a rare event. It made me think of ‘unicorn’ and how it has become the term of choice to describe the rare few startups that reach a valuation of more than $1 billion. Did I find the ‘unicorn’ equivalent in tennis?

To see how rare being at the top of singles and doubles has been in modern women’s tennis, I looked at the peak all-surface Elo MOV ratings each women’s player achieved in singles and doubles for each year since 2003. Based on the season best rating, I rank the players and then pull out the players who were in the top 5 for the season in singles and doubles. Players who competed in fewer than 8 matches in doubles in a given year are excluded; my logic being that a minimum sample size is needed and 8 seemed a reasonable choice as this would cover the case of good singles players who only compete in doubles at Grand Slams and get beyond the first round more often than not.

In a little over 15 years, only 7 women’s players have been at the top of the singles and doubles game in a single season. And only Serena Williams, like Barty, has been at the very top in both events at any point in her career. Now, if I was able to go back a bit further historically, I imagine Venus Williams and Lindsay Davenport would join that list as well. And if I were to go back even further, Martina Navratilova would clearly be a unicorn of the early WTA, a time when strength in singles and doubles was probably more common.

Focusing, for now, on modern times, this list convinces me that Barty is a rare breed. Barty’s average peak season rating of 2467, based on her performance so far in 2019, is only exceeded by Serena’s in 2009-2010 and 2012-2013. Note that, while Barty is currently the most highly rated hard court doubles player, Timea Babos actually has the highest all-surface doubles rating so far in 2019.

Season Player Peak Singles Rating Peak Singles Rank Peak Doubles Rating Peak Doubles Rank
2019 (To date) Ashleigh Barty 2536 1 2398 2
2013 Serena Williams 2766 1 2410 1
2012 Serena Williams 2669 2 2435 2
2011 Victoria Azarenka 2494 3 2363 3
2010 Serena Williams 2463 3 2482 1
2009 Serena Williams 2520 1 2417 1
2009 Venus Williams 2502 3 2409 2
2008 Dinara Safina 2470 5 2244 3
2003 Kim Clijsters 2464 3 2250 1
2003 Lindsay Davenport 2360 5 2140 4

It’s also interesting to me that Victoria Azarenka (the player Barty has teamed up with in multiple events this year) is the only other player to achieve unicorn status after 2010. And of the four other women who make the list— Lindsay Davenport, Dinara Safina, Kim Clijsters, and Venus Williams— only Venus Williams and Safina did so within the past 15 years.

Without Serena and Ash, the WTA would have had few occasions to see the best singles players making waves in doubles. It is a reminder of how much the men’s and women’s tours really seem like a collection of tours, with some players focusing exclusively on singles, some exclusively on doubles, and the rest dabbling in one or the other.

The fact that Ash has gotten to the top of the singles game while resisting the standard program of treating doubles as an after thought is interesting enough in itself. But what makes it even more compelling is that she has reached this milestone at time when doubles is generating so much interest. Some of the greatest moments of joy in the summer of tennis have been seeing Andy Murray’s doubles win in Queens and the debut of Murena at Wimbledon. And when we recall the delight of seeing Federer and Serena go head-to-head at Hopman Cup at the start of the year, it makes 2019 feels like the year of doubles.

But the sad reality is that doubles feels like it’s thriving in 2019 in large part because of the near retirement of Andy Murray. These aren’t the kind of circumstances that should have to arise for great players to play more doubles. But, with Hopman Cup going by the wayside and more singles and team events elbowing their way into the tennis calendar, tennis hasn’t left players many other options. We can already see signs of those pressures tightening in on Barty with her withdrawals from her two most recent doubles events.

If the sport could find a way to support players who have the potential to thrive in singles and doubles, we might find that unicorns in tennis aren’t as rare as we think.