Oh I agree. Bad knee or not, Rosol played incredible, especially in that fifth set. Deserved to win. But if Nadal needs to justify that loss to himself then fair enough - after all Federer seems to never have the confidence knocked out of him - not bad for Nadal to learn some of that... I think he recognises that Rosol was good that day, but he also tells himself that "I wasn't by best" - easier to accept losing to the world no.100 that way!
I really think he wasn't at his best, already thought that before but now his precisions about his knee condition are precise.
But no in the itw he doesn't recognize at all that Rosol was good that day : he says "it was not a game of tennis".
Besides, your Federer-reference is over the top : Fed never said about a match lost "it was not a game of tennis" (Fed relativizes it differently : he would say "it was just one tennis match", it is different : in Nadal's education there is always an explanation, Fed is rather about chance and fate "it's just tennis, can go this or that way, let's skip to next one")
You are clever but about Federer, it seems that you can't understand him well.
And it's far from the first time that Nadal says he was not at his best to "not knock his confidence out". Not something Federer does usually : Fed deals with it differently : it was just one match, it didn't turn his way ... No I don't see what Nadal learnt from Federer here (besides he had already said that "Tsonga hadn't "played normal" after his AO 2008 loss, never heard Fed say that)