With the ATP & WTA tennis schedule moving from hard court to clay court tennis bettors should be aware of the differences.
Clay events have very different characteristics to the harder surfaces, with fewer service holds, fewer aces and generally much longer rallies. Clay matches are arguably a stronger test of a player’s fitness level than other surfaces.
The table below illustrates the significant difference in service hold percentage and aces per game between clay courts and other surfaces:
| Surface | 2 Year mean service hold % | 2 Year mean aces per game |
|---|---|---|
| ATP | ||
| Clay | 75.7 | 0.35 |
| Hard | 79.4 | 0.55 |
| Indoor Hard | 80.8 | 0.58 |
| Grass | 83.6 | 0.65 |
| WTA | ||
| Clay | 61.9 | 0.19 |
| Hard | 63.8 | 0.25 |
| Indoor Hard | 63.1 | 0.26 |
| Grass | 69.6 | 0.31 |
With the difference so evident in the table above, the following table highlights the court speed of each ATP & WTA event for the clay court schedule in 2015 (sorted from fast to slow):
| ATP Tournament | Category | 2 Year Serivce Hold % | Deviation from Clay Mean % |
|---|---|---|---|
| Madrid | 1000 | 80.2 | 4.5 |
| Gstaad | 250 | 78.6 | 2.9 |
| Munich | 250 | 78.2 | 2.5 |
| Rome | 1000 | 77.7 | 2 |
| Houston | 250 | 76.6 | 0.9 |
| French Open | Grand Slam | 76.4 | 0.7 |
| Nice | 250 | 75.5 | -0.2 |
| Barcelona | 500 | 74.7 | -1 |
| Bucharest | 250 | 74.6 | -1.1 |
| Kitzbuhel | 250 | 74.2 | -1.5 |
| Hamburg | 500 | 73.5 | -2.2 |
| Bastad | 250 | 73.2 | -2.5 |
| Casablanca | 250 | 72.4 | -3.3 |
| Monte Carlo | 1000 | 72.1 | -3.6 |
| Oeiras | 250 | 71.1 | -4.6 |
| Umag | 250 | 70.9 | -4.8 |
Bettors should use this information in conjunction with this previous article, which looks at court data for fast and slow courts.
What the clay court data suggests
Interestingly the Madrid Masters/Premier - one of the biggest events on the clay calendar – appears at the top of both the ATP and WTA Tour and clearly has very fast conditions, which is likely to suit bigger servers. It will almost certainly not play as a traditional clay court.
Conversely, Bastad has low service hold percentages for both Tours, and conditions in Sweden appear to be very slow indeed. This is also the case for both clay events in Morocco (ATP Casablanca and WTA Marrakech). These events will favour the traditional clay courters.
ATP Gstaad - played at altitude - unsurprisingly shows up as a fast court, although surprisingly Kitzbuhel - which is also played well above sea level - does not.
How strong ATP & WTA returners perform on clay
Particularly in the ATP, certain players have a strong preference towards clay or hard surfaces, which results in a big difference in their results between the two surfaces.
We identified in previous articles how to tell a player who is stronger on return than serve by using the formula (service hold % - break opponent %), with lower figures indicating the player is strong on return.
From our list of the top ten ATP strong returners, only Matt Ebden isn’t considered close to a clay-courter – meaning the list highlights players who favour clay courts.
In comparison the WTA list is far less biased towards clay-courters, and only Chanelle Scheepers, Sara Errani, Estrella Cabeza Candela and Lourdes Dominguez Lino would be considered much better on the dirt.
The table below illustrates the records of strong ATP and WTA returners on clay in their last 50 matches on the surface, with Pinnacle’ closing prices being used from a £100 hypothetical bet on each players’ match:
| Player | Last 50 Clay Matches | Wins | Win % | P/L | ROI |
|---|---|---|---|---|---|
| Andujar | 50 | 28 | 56 | 446 | 9.5 |
| Monaco | 50 | 29 | 58 | -453 | -9.2 |
| Lorenzi | 50 | 26 | 52 | -741 | -16.5 |
| Fognini | 50 | 35 | 70 | 1073 | 21.9 |
| Ferrer | 50 | 39 | 78 | 345 | 7.2 |
| Berlocq | 50 | 32 | 64 | 1018 | 20.8 |
| Ebden | 23 | 6 | 26 | -1075 | -71.7 |
| Falla | 50 | 25 | 50 | -761 | -16.9 |
| Garcia-Lopez | 50 | 30 | 60 | 1444 | 28.9 |
| Gabashvili | 50 | 31 | 62 | 1914 | 40.7 |
| ATP Returners | 473 | 281 | 59 | 3210 | 6.8 |
| Beck | 50 | 30 | 60 | -836 | -16.7 |
| Scheepers | 50 | 28 | 56 | 354 | 7.1 |
| Errani | 50 | 39 | 78 | 378 | 13.1 |
| Radwanska U | 50 | 19 | 38 | -64 | -1.7 |
| Hsieh | 50 | 23 | 46 | -574 | -27.3 |
| Dolonc | 50 | 24 | 48 | 146 | 5.6 |
| Cabeza Candela | 50 | 27 | 54 | -636 | -20.5 |
| Niculescu | 50 | 24 | 48 | -466 | -12.6 |
| Koukalova | 50 | 26 | 52 | -868 | -18.1 |
| Dominguez Lino | 50 | 33 | 66 | 354 | 7.5 |
| WTA Returners | 500 | 273 | 55 | -2212 | -4.4 |
It’s clear that ATP strong returners have an edge on clay, returning 6.8% from 473 matches. And If we filter out Ebden, who was identified as a player who doesn’t favour clay courts, this increased to 9.5%.
On this basis, it appears that the markets are under-rating ATP clay courters who are strong on return.
The WTA players list is much more random, and the betting success evident in the ATP is not replicated on the women’s tour.
However, of the four women’s clay courters previously identified, three - Sara Errani, Lourdes Dominguez Lino and Chanelle Scheepers - were the most profitable from the sample.
Even when including Estrella Cabeza Candela - who has dropped to 300 in the world - they generated a return of investment of 2.25%.
Clay Court betting strategy
The data indicates that clay courters whose strength lies on return are clearly under-rated by the pre-match betting markets and bettors should factor this into their decision making in subsequent clay court tournaments this year.
In addition, tennis bettors should take notice of the differing clay court conditions and note certain events fluctuate quite dramatically from the clay court mean.
