He lost the match, didn't he? Poor fitness or whatever else the reason, he lost. When he beats Nadal again, on any surface, we can start talking, until then this is a moot point. And considering Nadal is a far heavier favourite at RG than any other player at any other event, his chances there aren't all that great. Besides, he would have to get to Nadal first and he might have to beat Djokovic and/or Federer for that to happen. I'd say he is far more likely to win another USO title.
He lost 6 in a row to Federer this year, so let's stop pretending Nadal is the only obstacle here.
Yup, he did lose the match. But if we are going to scratch everyone who lost to Nadal on clay/has losing records against Nadal on clay, might as well just hand him the trophy already. He lost the match, but not in a way that suggests he has no chance against Nadal on the surface. Maybe it was just me, but when watching it I felt he was very capable of beating Nadal on the surface (one day), the best chance of anyone on tour along/bar Nole.
He could face Nadal in QF (ie not have to go through Fed/Nole), I hope he does. Any path to the RG title (for JMDP or any other player) will necessarily involve Rafa, and facing him in the QF is a far less scary proposition than doing so in the final.
And yes, Nadal is far from the only obstacle, but when we're discussing a player's chances at Roland Garros how he matches up against Nadal is always important since Nadal has reign supreme there.