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Hard Courts v Clay Courts – Rally Length Differences

The big two tournaments of the Spring hard court season, Indian Wells and Miami, are upon us. The day after Miami crowns its champion, we’re into the European clay court season with Monte Carlo the first ATP 1000 event.

The old story of hard court versus clay court tennis was always that clay was for “grinders”. Are rallies longer on clay than on hard courts? It was certainly true as far back as I can remember, but according to some experts, times have changed…..or have they?

True or False – Rally Lengths are very similar on both surfaces

When it comes to rally length ranges – ie 0-4, 5-8, 9+ - the modern story goes that the percentages of these rally lengths occurring, as an average, across all professional tennis, does not change from hard courts to clay courts.

If you watch a lot of tennis, you’re thinking that just can’t be true……can it? It’s so counterintuitive, even in the crash and bash of the modern game there are still more long rallies on clay courts than hard courts?

We set out to prove that long rallies dominate clay court tennis……but we couldn’t. If you look at an entire tournament on clay and an entire tournament on hard court, the rally length range occurrence rates are incredibly similar.

Is that the end of the debate?

In an article I wrote for The First Serve last year, I mentioned the pitfalls of “big data”. That is, the focus we have these days on grabbing thousands of points across all players, rather than paying attention to how the individual plays the game.

While the premise of big data is fine – in this case that rally length ranges are similar across surfaces – it fails to break down and individualise the data to make it more useful for a player, no matter what their age or stage of tennis.

The simple fact is, if rally length data was the same, why hasn’t John Isner gone deeper in the draw at the French Open, or any other clay court tournament for that matter? If players have better results on clay vs hard courts, and they do, surely part of the reason is something to do with the length of the rallies?

It is!

A Quick 135 Refresher from Last Year

“The server and the point winner are the easy [stats] in our story. Rally length is a little more detailed…

The bulk of points in tennis finish on shot 1, shot 3, or shot 5 ie the first 3 shots played by the server in any given point. It’s no coincidence that the analytics system we established to measure player performance is called ‘135 Tennis Analytics’.

Then there’s the returner’s first 3 shots: 2-4-6, and lastly there’s the long rallies, which go 7 or more shots, collectively called 7+.

The important thing to realise is that, if we talk in server’s shots and returner’s shots, we’re talking about a sequence of shots made by a player, NOT both players. 5 is often related to 3, which is related to 1, for example. We’re not grouping in 0-4 which, because it’s a range, has nothing to do with who hit the shot.”

Original article on this link

Now that we’ve got that out of the way, let’s move on.

135 Occurrence Rates

The percentage of time that points finish on shot 1, 3 or 5 (collectively known as the combined rally length 135) is around 50% on both the ATP and WTA tours. That’s big data which we can obviously personalise when profiling players.

John Isner, for example, finishes points on 135 on his own serve around 80% of the time. Australia’s John Millman, more like 40%.

A player’s stature doesn’t necessarily dictate their 135 profile. Diego Schwartzman, at 5’7”, finishes on 135 on his own serve around 55% of the time. Ash Barty around the same during her career. Both slightly above average.

The REAL difference between the surfaces

Again, we’re talking about big data, but in the pro ranks the 135 occurrence rate doesn’t

change very much from hard court to clay court, similar to 0-4, 5-8 and 9+.

The real difference is that players are having to play one, or perhaps two, more shots on a clay court compared to a hard court. So, they’re not necessarily having to grind out a 50 shot point on clay on a regular basis, but a lot of the time they’re playing one more shot.

The implication being that there are generally less 1s (aces and unreturnables), and more 3s (first shot after the serve) on clay. Some of the 3s on a hard court turn into 5s on a clay court. So 135 is similar. It’s just where in the sequence the point finishes that can change.

Sometimes a player’s 135 occurrence rate drops on a clay court compared to a hard court. We looked at Djokovic v Nadal in a match on clay and then another on a hard court to compare their numbers:

135 down 13% 246 up 12% 7+ up 1%

What’s happening? Simply, the server is not as dominant on clay as the returner can do more with their return patterns. The points that go into the 7+ (long rallies) hardly move at all.

Notice that under this scenario, the 0-4, 5-8 and 9+ wouldn’t move around much either.

Implications for Developing Players

The first thing is to understand that there is a difference in rally length from hard court to clay court, but it’s a one or two shot addition rather than what we perceive to be a 30 shot difference on clay.

The second implication is to look at big data for what it’s worth: interest. Deciding to practice one tactic or strategy over another because that’s what the big data says will never take into account the need to personalise profile data for each player. We’re looking forward to working closely with Tennis Canada on this in the coming year.

Author’s Bio: Nicholas Scott is the Co-founder of 135 Tennis Analytics, and co-developer of the 135 Tennis Analytics framework. Nick has worked with ATP and WTA pros, college and high school tennis teams and coaches, and national federations like Tennis Canada. For more information, visit


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