The bolded part is so true, that is what bothers me about excuses in general.
As for this match, Nadal won easily in the final in Rome after having a long match against Davydenko in the semifinal. Besides, Nadal won easily against Youzhny in Paris when Youzhny had an exhausting match against Haas the previous day. I don't recall Nadal fans saying on that occassion "oh, a piece of good luck for Rafa, Youzhny is normally a bad matchup for him"
Generally, a fair assessment. But in this particular match nearly everyone who said Rafa was tired also qualified that statement by saying that he would have lost anyway.