Everybody who beat Nadal at Wimbledon during this time (with, in my opinion, the only exception Darcis) played insanely aggressive and had a huge game. Rosol, Kyrgios, Brown and Muller were towering guys with an overpowering style of play on grass. Even though he won Wimbledon twice, this was Nadal’s least favorite surface. One could also argue that the shifting speed of the grass every year played a role in his success (this is not taking away what he has accomplished but history is never as linear as people hope it to be)