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The stat behind Rafael Nadal's clay-court success

The Euroclay season is well underway, with the major ATP Masters 1000 events coming up the next few weeks in Madrid and Rome. The women will join them in both locations. This week, the Racket Scientist will take a close look at how some of the men play pressure points -- and the hottest WTA player thus far on dirt.

Big Four break-point challenge

It should come as no surprise that Rafael Nadal is listed as No. 9 on the ATP MatchFacts list of men who have been most successful converting break points on clay. The King of Clay has cashed in on exactly 50 percent of his break-point chances in 339 matches (1,575 of 3,181). But there are always a few caveats when it comes to these statistics.

For starters, Nadal actually is a co-No. 8 on that list because Juan Aguilera, like Nadal, is also at 50 percent. The bottom line is that just seven men have a better conversion rate than Nadal -- or Aguilera.

Nadal's record looks even better if you take into account the sample size on which the stat is based. One weakness in ATP MatchFacts is that the bar for consideration, while it exists, is set low. The best career break-point converter happens to be Ulf Stenlund, who was successful a mind-boggling 82 percent of the time.

But Stenlund played only 70 matches on clay, and he had just 11 break points. While it's admirable that he was able to convert nine of those, Stenlund probably qualifies for a unique honor: tops in break-point conversion while being perhaps the worst serve returner in tennis history. At least it appears that way, if you base it on his average of one break-point earned for every 6.3 matches.

If you set the bar at a minimum of 100 matches played and at least 100 break-point opportunities, Nadal trails only Jan Gunnarsson, who faced 155 break points in 189 clay-court matches and converted 52 percent.

Surprisingly, Nadal's Big Four companeros -- top-ranked Novak Djokovic, Roger Federer and Andy Murray -- are significantly lower on the list. The number of pros who are deadlocked at a certain percentage increases significantly as you start dipping into the mid-40 percent range, but there's still a lot of distance between Nadal and his peers.

Djokovic is next best, with a 45 percent conversion rate (756 of 1,683). But that's good enough only to leave him tied with a bunch of people in the No. 32 spot (in other words, 31 guys logged 46 percent or better). Murray is a true No. 93, with a 43 percent rate (348 of 891) in 91 matches, while Federer is a true No. 215, having converted 40 percent in 246 matches (883 of 2,187).

One other caveat: The numbers for the active players are always in flux, and they probably get worse rather than better in a pro's final active years.

Kerb your enthusiasm

Angelique Kerber was down to No. 16 in the WTA computer rankings after the Miami combined event and riding a nasty 3-8 record dating to the Australian Open. It looked like she was on her way to 3-9 when she found herself down a break in her first-round match immediately after Miami on the green clay of Charleston. But she found a way to win that match and the tournament, and she was off and running.

As of the beginning of this week, Kerber is undefeated on clay, with two tournament wins and an 11-match winning streak. Charleston was her first tournament win since Linz in early October 2013. With that in mind, I checked to see who among the WTA top 10 has been on an extended title drought.

The top five (in order): No. 1 Serena Williams, Simona Halep, Maria Sharapova, Petra Kvitova and Caroline Wozniacki have all won tournaments in 2015. In two weeks' time, No. 6 Eugenie Bouchard will celebrate the first anniversary of her sole tournament win, in Nurnberg. No. 7 Ana Ivanovic last won in September (in Tokyo), and No. 8 Ekaterina Makarova hasn't won in roughly 15 months -- since last year in Pattaya City.

Agnieszka Radwanska, now ranked No. 9, last won in Montreal in early August 2014, and No. 10 Carla Suarez Navarro would be celebrating her first tournament victory at Oeiras this week in Portugal -- except the women's event there no longer exists.

What stagnant economy?

Wimbledon is continuing to play the game of financial one-upmanship that has been raging in tennis for some years now. The All England Club announced on Tuesday that prize money would rise again this year to more than $40.60 million. The singles winners in each Open division will haul in $2.85 million.

That's the greatest prize-money pot ever in tennis, surpassing last year's US Open ($38.25 million). In four years, the size of the Wimbledon purse has nearly doubled -- and the top dogs haven't been the only beneficiaries. First-round losers (something that you and I could easily be if only we were allowed to sign up for the tournament) also got a hefty 7 percent boost and will now take home $44,500.

Wonder if the tournament swag bag includes a wheelbarrow.