During yesterday’s broadcast of the Australian Open match between Alison Riske and Yanina Wickmayer, commentator Elise Burgin discussed whether the depth of the WTA has increased over the years. She felt strongly that it has, and she had a very useful illustration on screen, as 55th-ranked Riske was putting on an impressive display of shotmaking en route to a 6-1 6-1 victory.
From a quantitative perspective, “depth” can be hard to pin down. If lower-ranked players are holding their own against the top five, or ten, or thirty, it could mean that the field is very deep, or it could mean that we’re in an era without all-time greats. As Burgin pointed out, the WTA might not currently have a top five to match those of some recent eras, but there’s little doubt that today’s top two could line up with just about any of the last few decades.
It would be very difficult to settle whether today’s top ranks are good, bad, or otherwise in historical terms, so for now, let’s assume they are average. We’ll return to that in a bit.
Let’s start by looking at how the WTA top 32 has fared against everybody else. This encompasses about 900 matches per season. The trend isn’t overwhelming, but it does seem that the top 32 is not quite as dominant as it was in some previous periods:
The 2012 and 2013 winning percentages of 73.4% and 74.7% represented the lowest two-year span since 1984 (where my ranking database begins). Aside from the outlier years of 2004 and 2007, the top 32 has won fewer than 77% of its matches against the pack for more than a decade. In the 1980s and 1990s, the top 32 was consistently above that number.
Of course, drawing the line at the top 32 is arbitrary. Most of us would think of the 19th- or 26th-ranked player as part of the pack, not as a defining player of this generation. Let’s see how the graph looks if we draw the line at the top 10:
Looking at the top 10 against everyone else doesn’t differentiate the current era quite as much as the top 32 does, but it continues to show that the pack is quite competitive in historical terms.
Since 1984, the top 10 has won almost exactly 80% of matches against everyone else, and for the last two years, the WTA has matched that number. However, in the very recent past, from 2009 to 2011, the pack posted the three best single-season records against the top 10, peaking in 2010, when the top 10 won only 74% of matches against others.
As I noted at the outset, comparing “the top” with “the pack” in a series of years implies that one or the other is a constant. The top–especially a small group such as the top 10–almost certainly isn’t. In 2010, that great season for the pack, Serena Williams played only 29 matches, compared to 62 in 2009 and 82 in 2013. Add another 30 or 50 Serena matches to the sample and maybe the pack wouldn’t have looked so good.
While the pack is less affected by single injuries, it probably isn’t a constant either. After all, the claim that launched this post is that the pack has improved. Thus, we can’t entirely trust these numbers as a rating of the top based on their record against the pack, or as a rating of the pack based on their record against the top.
However, we can see broad trends and supplement them with some qualitative judgments. If you believe that today’s top ten is a particularly weak one, the fact that the pack is winning only 20% of their matches against that group isn’t exactly an endorsement. If you think the top of the game is particularly strong, that 20% looks much better, supporting Burgin’s position that the pack is better than ever.
An alternative theory that may explain this intuition about the pack is based on injuries. WTA injury numbers (based on retirements and withdrawals, anyway) are at an all-time high, and advances in sports medicine are getting players back on court quicker than ever. Thus, there is always a pool of players whose talent level is not represented by their ranking, either because they are injury prone and never reach that ranking, or because they’ve recently missed time and seen their ranking fall during that period.
Of course, there have always been players in the field returning from injury, but at any given time, there are probably more today than there were twenty years ago. And that means more unseeded, lower-ranked competitors with the capability of beating a top player. They usually don’t–as in the cases of Andrea Petkovic, Venus Williams, and Vera Zvonareva this week–but if you’re looking at a draw hunting for dark horses and interesting early-round matchups, those are the sorts of names that deliver.
Given all the moving parts in this sort of analysis, it’s tough to draw conclusions. If a couple of players suddenly emerge as dominant players and complement Serena and Vika at the top of the game, we could see these numbers swing in favor of the top. If Serena suddenly retires, they’ll probably swing in favor of the pack. For now, the best I can offer is that the pack–whether defined as those outside the top 10, top 32, or any number in between–is probably a bit better than the WTA’s historical average.