He already had a lot of rest between his RG loss and Wimbledon.
For some reason he just can't find the form he had last year. Maybe he had trouble going back to clay after playing on grass. Maybe it's the issues in his personal life. Maybe he's still a bit injured. Before the match he also complained about the heat on Twitter. I don't know, this is just a crappy year for him, especially compared to the last. At least he has that mixed doubles title.