Hey, nice to see someone taking an interest in match stats. You can find match stats from past years at Web Archive: http://archive.org/web/web.php. For example, you can run a search there for the official U.S. Open site in past years, by searching for the address "www.usopen.org." I'd agree that Nadal, playing well, wins a great deal of points on the unforced errors of his opponents. But I've seen some matches of his in which his high level of play is reflected in the differentials, too, even when he's playing someone who makes many more winners, and errors, than he does. When he beat Verdasco at the 2009 AO, in a match praised for its quality, he made 52 winners and 25 unforced errors compared to Verdasco's 95 winners and 76 unforced errors. Verdasco's a perfect example of someone whose game is much more based on hitting winners, when compared to Nadal. Verdasco had almost twice as many winners as Nadal. But his differential is not larger than Rafa's. Nadal had a winner/error differential of +27, Verdasco +19. I follow your logic and what you're saying may be true, it's just that Nadal, though he may "provoke" a lot of unforced errors in his opponents, also keeps his own unforced errors very low, which allows him to have better differentials than his defeated opponents. Nadal's case is a little tricky, because he generally makes few winners and few errors, compared to some high-risk players out there; but there are some matches in which he does totally unexpected things. For example he lost the 2006 Wimbledon final to Federer in four sets. But his differential (+16) was better than Federer's (+11). That's because he made fewer unforced errors than Federer, as usual, but he almost equaled Federer in winners (42-43) -- something you would not normally expect him to do. The differentials give the wrong picture of the match because they are built on official stats which only report UNFORCED errors. The forced errors are almost never reported in official stats. In this match, Federer actually won a lot more points, overall, than Nadal did. But he made more unforced errors than Nadal; and in winners he had no real edge. That tells you that in the category of FORCED errors, Federer must have been doing most of the forcing. Sometimes the dynamics of a match -- or even a rivalry -- just fall "outside the box," so to speak. Or problems could arise from the way that statisticians at a particular tournament are judging their unforced errors. The other Nadal/Federer finals at Wimbledon, in 2007 and 2008, also have problems if you go by the differentials. There is one method that does count the forced errors. It's called the Aggressive Margin, maybe you've heard of it. You can read about it here: http://www.itftennis.com/shared/medialibrary/pdf/original/IO_24691_original.PDF Basically, in tennis you want to be as aggressive as possible while making as few errors as possible. That's what the Aggressive Margin measures. It measures the points that you win aggressively -- either by striking clean winners or by forcing your opponent into errors -- and compares that with how many points you gave away by making unforced errors. To have a high Aggressive Margin does not mean that you have to be what we normally think of as "an aggressive player." The guy who makes few winners and few errors, like Nadal, can have just as high an Aggressive Margin as a guy who makes a ton of winners and errors. What matters is whether you can win points but not pay too high a cost in errors. Whoever does better at that balancing act has the higher Aggressive Margin and is almost always the winner of the match. When you calculate Aggressive Margins for the Federer/Nadal finals at Wimbledon, those matches start making sense. Federer’s Aggressive Margins against Nadal at Wimbledon: 30.5% (2006) 33.1% (2007) 30.3% (2008 ) Nadal’s Aggressive Margins against Federer at Wimbledon: 22.4% (2006) 31.0% (2007) 31.5% (2008 ) These matches are tightly bound up; there's not a lot separating them. Except for Nadal's performance in 2006, all the performances were pretty much of the same quality. In fact they are so similar that you could argue that Nadal performed better in 2007 than Federer did in 2008: but only by a slight margin. The similarity of the 2007 and 2008 finals in quality is also borne out through other methods -- like calculating the percentage of total points that ended with a winner. And I think if you just watch those matches, you feel that the 2007 and 2008 are very similar; and that the 2006 match was a solid win for Federer unlike the struggles of the other two years. Federer has higher Aggressive Margins than either Nadal or Djokovic -- and I will post those, I have several dozen spanning their careers -- but I just wanted to say in passing that the highest Aggressive Margin I've ever calculated belongs to John McEnroe in the 1984 Wimbledon final: 52.8%.