It would have been interesting had he won the 4 slams in a row, but he didn't.
Yep. Once in a lifetime shot, there's no way he should have lost to Federer at Roland Garros with last year's form. Nadal in the final I suspect would have been just as easy as in Rome and Madrid.
Where he probably went wrong was winning _everything_ the first half of last year. He ended up with a crapload of matches under his belt.
Now? He's probably just the best hard courter, but at 25 he's not going to rack up enough slams with Aus/US alone, unless Nadal's injury problems become chronic - if so, he could potentially win 7 of next 8 or the like. Then he's in the GOAT conversation.