The grass being slower at Wimbledon than in the past certainly helped Nadal. Some of his amazing saves would have been winners for Federer without it and in a match that close, it wouldn't have taken too many to change the outcome.

And, while I hope it was written tongue-in-cheek, Nadal's awesome biceps do nothing to give him power. You don't need huge arms to hammer a tennis ball, which explains why Federer with his stick arms can have a harder serve than Nadal.