Wait a second. Nadal is an 'all-court player'?? WTF? The man can't even step foot on a hardcourt without his knees dropping off.
Djokovic and Murray are by definition all-court players. It just happens to be that Federer is amazing on grass while Nadal is unbeatable on clay.
Djokovic is more all court player than Nadal is.
Nadal got lucky with USO. and Nadal has never been able to defend hard court title.