Yes, if you think about the surfaces in the last year, the current top 3 are probably in this order:
Grass: Federer >> Murray >>> Djokovic
Hard: Djokovic > Murray >> Federer
Clay: Djokovic > Federer >>> Murray
So Federer has a natural advantage. Still, ******** could turn up. Fed wins 7/10 times on clay, I'd say.