When watching a tennis match you’ve undoubtedly seen the statistic flashed on the screen: ‘Break Point %’, or something similar. That is, the amount of times a player converted a break point when they had a break point opportunity. You may even have seen the statistic, tracked over the course of a season, percentage of return games won. Successfully returning serve is arguably the most important part of winning in tennis, so it’s good that we have metrics that attempt to show return of serve prowess. Unfortunately the two statistics I’ve mentioned are inherently flawed and can often lead us to false conclusions.

Break point conversion rates sound like a good metric; how often did the player win an important break point when they had the chance. But this percentage on its own can often disguise what really happened. A player who has five break point opportunities and converts on two of them has a break point conversion rate of 40% (the average for most ATP players). But let’s say their opponent in that match had ten break point opportunities and converted on four them. Their percentage is also 40%, but they broke twice as many times. This is where I feel the statistic is flawed.

There may be a game where you get the score to 30-40 in your favor, win the next point, and your break point conversion rate is 100%. Or you could have a game where you go to several deuces, back and forth, and finally convert on your fourth break point opportunity in that game. Your conversion rate is 25%. Why should we care how many tries it took you to break as long as you do actually break serve in the end? The end result is the same. While it’s true a better returner may convert within that one game on fewer opportunities, it’s irrelevant really. You don’t get bonus points in tennis for being efficient.

Percentage of return games won aims to correct for some of the shortcomings of the previous statistic. You get the frequency with which someone breaks and nothing else. Sounds pretty good. As far as measuring just returning ability this statistic works fairly well. But when evaluating a player as a whole, it too can mislead. Say you’re on serve with your opponent at 3-3. You get a break and go up 4-3, but on your very next service game you’re broken back and the score is again tied, 4-4. Yes, you broke your opponent so your percentage of return games won increases. But you were immediately broken back which negated your great return game entirely. A break is only useful if you keep the advantage. So sure, it’d be great to have 50% of return games won, but if you are immediately broken back half those times, you’re not getting ahead of your opponents very often.

With that being said, I’ve created what I think is a more comprehensive (though not perfect) statistic called Effective Break Percentage (or Proportion), or as I’ll refer to it, EBP. The formula for the statistic is as follows:

**(Breaks – Breakbacks) / (Games with Break Chances)**

That is, the number of games in which the player successfully broke their opponent’s serve less the games in which they were immediately broken back (excluding times when serve was broken to win the set). That number is then divided by the number of games in which the player had at least one break point opportunity. To further clarify: over the course of a match you have break point chances in 8 games, you actually break in 3 of them, and after one of those games your opponent immediately broke you back. Your Effective Break Percentage for that match is ((3-1)/8) or 2/8 or 25%.

This statistic isn’t entirely without faults. In percentage form, you still face the issue of 1 out of 4 being treated the same as 3 out of 12. So when looking at an individual match, I believe it’s better to leave it as a proportion. Over the course of an entire season though, the amount of games should be high enough to more accurately show who’s more proficient at earning and keeping breaks. I’m open to suggestions on how to account for the discrepancy in individual matches, though.

It’s also a difficult stat to actually compute. You can’t really retroactively go and calculate this percentage without point-by-point breakdowns of matches, which are only available for majors, as far as I know. So unless the Tennis Channel decided to adopt this idea, you’ll have to carefully track the points when watching a match.

So why bother? Well, break points have been considered by many to be the most important statistic to focus on in determining the winner of a match. Research has been done to show that that may not actually be the case. I’m not convinced entirely, though. In the future I’d like to test the predictive power of EBP and see if it explains wins any more than break point conversion does.

What’re your thoughts? Is it a useful statistic worth tracking or just as unreliable as break point conversion? As mentioned, any suggestions on how to improve this is much appreciated, and hopefully I can work with the data further in the future.

Hello,

I enjoyed reading your thoughts on break points, but I feel there are several issues that I would like to mention, although by no means am I certain that I’m right, simply posing a response to your theory.

You argued that 1/1 break ratio and 1/4 in the same game is the same in the end because it achieves the same result. This is true if we were simply going to look at the result for that game, but a long term look at the stats makes a big difference. It’s why casinos make money instead of going out of business. They look at stats in the long run. If I want to be an effective returner, it would be helpful to know on average how many break points I would need before I could achieve the break. It tells me how well I play big points. It should not be the defining statistic in determining a returners effectiveness, but like every statistic it has it’s place and usefulness.

The other issue I have is not the usefulness of EBP, but rather it is not measuring a player as a returner, but a player as both a server and a returner. I don’t believe it’s fair to discount break point percentage (measuring player as returner) because EBP measures more. Your EBP is a fascinating number and concept but instead of being a replacement for break point percentage, it would be an incredible complement. If I have a player I would take the break point percentage as a measure of returners effectiveness, and then use EBP to determine the effectiveness Of holding serve after breaking.

Again, I think your EBP is a great concept and I will begin to use it in my own coaching, but I am not willing to throw out break point percentage and ratio. Raw numbers tell us only facts. Wisdom allows us use them to our advantage. I would rather have as many numbers as I can at my disposal. Thanks for sharing your theory and I would appreciate your thoughts on my thoughts

First off, thank you very much for the well thought out comment and encouraging words.

I’ve come to rethink a few things since writing this post, and I tend to agree with most of your points.

I’m still a proponent of the idea that number of break points in a game is mostly irrelevant and that it comes down to whether you convert or not. I guess a better way to look at it would be as ‘break games’ instead of break points. That way you still get the long term stats; how many games with break opportunities, on average, do you need to finally convert that break. Points alone still do more to skew that, in my opinion. Especially if you want to look at skill in playing ‘big points’. Say you’re in a tight back and forth deuce game where you have six or seven deuces and four break point opportunities. Converting on that fourth break point and winning that game is a huge win, and means you did well in playing the big points, just to give yourself an opportunity to win that game. It would misrepresent that game to say you had a 25% conversion percentage (which is relatively poor), when you still did well to win the game.

I also agree that as I continued to think about this stat, it became a bit more than just return effectiveness. I definitely think it serves as a good complement to other break related statistics, and perhaps its not as useful as I had originally imagined on its own. It’s true that if you had a break point percentage and an EBP side by side, you’d likely be able to glean significantly more about player performance than you would with either of those on their own. As I mentioned in the original post, I’d love to run a regression and see if EBP was any more revealing about who wins the match than traditional break point percentage and other similar stats. I think it may be, but that may be because more than just returning is involved in the number.

Thanks for reading and I hope you’ll come back to check out future posts!

Hello sir,

As I look back at what you and I have written, I think we both have fallen into the deceptive (not with a bad connotation) trap of what I would call being good coaches:). What I mean by that is we have entered the realm of taking quantitative facts and trying to explain their usefulness with subjective perspectives. It is in doing this that neither of us is rght or wrong, but rather we are taking the numbers and using them to our advantage. There is nothing wrong with that I think, but it is a matter of perspective. You are very correct in that winning the 4th break point in a long game I major mental victory, and could just as easily show the player to be effective at playing big points as it would showing them being ineffective. I think our difference is that my focus is not in one game but on the long term. A 25% break ratio in one game is in actuality a 100% games broken ratio for that one game as you very correctly suggested. My concern in the long run is really what the flip side of that stat tells us: that the opponents have 75% chance of getting another chance to win the game, and I will again use the example of the casinos as one of the reasons I am hesitant to throw out this stat.

After a bit of thinking, I would then propose this: adding another statistic (haha). My theory would be that we would first need to determine ratio of break points to total return points played. In other words, getting your first break point in the second deuce is different than at 0-40. If we could determine then the average number of points to get a break point ( I.e. 1 break point every 9 points) we would have the average frequency of break points. Then, we determine the break point conversion ratio, followed by, but used in conjunction with, the break games won to break games played ratio, followed by EBP. These numbers would (after you recover the dizzying vertigo of staring at numbers), give us a better and more quantitative foundation from which we could then begin applying subjective feedback to the player.

I definitely like your idea of looking at average frequency of break points. That’s a very useful stat, and I may go see who the current leaders on the tour are in such a stat. Should be interesting.

I’d love to create something that incorporated all these numbers, but at the risk of making things more muddled I think I’ll just leave it as is for now.

Thanks for challenging me on some of these points and expanding my thoughts about the subject. That was my main goal of this blog (to learn), so I’m glad it’s working so far.

I always enjoy learning as well. I hope to do this again 🙂