Head to Head statistics can be very deceiving. For example, Nadal has a lifetime edge over Federer of 13-7. What does it mean? It really doesn't mean that much. Federer's game doesn't match up that well against Nadal's game. But, who is the better player?
Of course, Roger wins hands down. Soderling beat Nadal recently at the French Open but was soundly beaten by Roger. Also, Roger again defeated him at Wimbledon. I will use my own case as an example:
I like to play table tennis and, at one time, was considered not bad. I was the base champion two years in a row at Griffiss Air Force Base in Rome, New York. But, certain players gave me problems. These players usually used a great amount of English.
One of them even had an even record with me. But, I was the Champion and he was only an also-ran. We never met in a tournament because he was always eliminated early. If your style, was a good forehand along with a lot of speed. I would eat you up.
Ok, back to tennis. Murray also has a lifetime edge over Roger of 6-2. Djokovic fares well against Federer although Roger has an edge. So, are these players better than Roger? Of course not. Federer is, by far and away, the Greatest Of All Time (GOAT.) I propose a statistic that, in my opinion is more meaningful than head-to-head. I call it Player to Player Stats.
The following example will apply to Murray, Djokovic, and Nadal against Federer. Federer won the Madrid 1000 Masters and then won the French Open. He will get a point for each tournament in the Player to Player. Ie, Federer vs. Djokovic, give Federer two points.
Federer vs. Murray, give Federer two points. Ditto, Federer vs. Nadal. If Roger wins Wimbledon, he will get an additional point against Djokovic and Murray but not Nadal because he wasn't in the tournament. This is even though Roger never faced any of them head-to-head in these three tournaments. If you actually meet a player head-to-head and win, you get one point if you win.
Roger has never faced Rafa in the U.S. Open but would gather four or five points in the Player to Player stats against him depending on how many times Nadal was entered from 2004-2008. Nadal didn't face Roger at Monte Carlo or Rome. But, Rafa won both tournaments and Roger was entered. So Nadal vs. Federer, Nadal gets two points.
I think that Player-to-Player is more meaningful than Head-to-Head. I really don't like the name but can't think of a better one.