Break Points are More Decisive for WTA

Last week I openly admitted to a new obsession with break points, which has lead me down a path of investigations to try to understand the role of break points for winning in tennis. One product to come out of this is the concept of break point decisiveness, which I define as the percentage of matches in which the winner also won more break points than the loser. My last post showed that break point decisiveness ranges from 87 to 91% for the ATP, depending on which surface and match format (best of 3 or best of 5) is being played. In this post, I turn to the WTA to see if break points have a similar link to wins as they do for ATP.

Mona Barthel defeated Stefanie Voegele in today's Luxembourg Open semifinal, winning 4 break points to Voegele's 1 and advancing to a final against Misaki Doi.

Since 2011, the frequency that the winner of a match also had an edge in break point conversion ranged from 91-93% for the WTA (Figure 1). The decisiveness for break points was highest at Grand Slams but all of the frequencies by tier are within their error ranges, so there isn’t strong evidence that break point decisiveness differ by tier.

Are there differences by surface? The frequency of a break point edge was also between 91 and 92% for all surfaces (Figure 2). This contrasts with what was observed for the ATP, where it was found that break points are slightly more decisive on slower surfaces.

Other differences between the ATP and WTA are also notable. In particular, regardless of surface, the decisiveness of break points is 3-4 percentage points greater for the WTA than the ATP (Figure 3). The flipside of what this tells us is that, compared to the ATP, it is more rare for a player on the WTA to win a match based on tiebreak performance or to come back from a set down in which the opponent had more of an edge in break point conversion than the match winner had in the sets she won.

When we look at the bottom 20 and top 20 players with respect to break point decisiveness, we find several surprising things (Figure 4). First, although more of the top players are among the group for whom break points are the most decisive, we do find one Grand Slam champion (Francesca Schiavone) and two finalists (Dominika Cibulkova, Vera Zvonareva) in bottom group. Also, the rankings in the top group do not exactly align with WTA rankings. Most notably, Caroline Wozniacki, who has had a break point conversion edge on 95.3% of the matches she has won, is the top of the list and slice maven Monica Niculescu is fifth, with a decisiveness frequency of 94.1%.

Given that Wozniacki is generally regarded as one of the more consistent players on the WTA tour, the rankings shown in Figure 4 suggest that break point decisiveness might provide some insights into consistency of play in matches a player has won, where a higher decisiveness than average would suggest more dominance in play outside of tiebreaks. Breakdowns of break point dominance by set are harder to come by for both tours but is the kind of data that would be needed to better interpret break point decisiveness and what it can tell us about a player’s consistency.