It might be me - but they've taken into account the last 70 matches Novak & Rafa have played. Aren't the %s based on matches played? In other words - why have they taken into account those two's last seventy matches - but are only figuring the % based on Ivan's last 53 matches played - for instance? Why not arrive at the individual %s based on the same amount of matches played by each?
Sorry for the confusion.
Because Ivan only played 53 matches this year. They count ALL the matches played in this year, for all players. For percentages, it doesn't matter how many matches were played, except if there were too few matches (like 5 or so) from which you can't draw any statistical conclusion. I mean, a guy might have played like 2 matches, saved 2/2 BPs and he would top the list at 100% BPs saved. That's why they only include players with the same order of magnitude of matches played as those who played most matches this year. That pretty much includes most of the top 100 players.