2011 was one of the best season in tennis history (3rd best season in Open Era). It wasn't odd, Djokovic was that good. Was Fed 2006 odd too? don't think so.
Roger had 2 seasons of similar level before and 1 after. 2006 wasn't a fluke year.
Djokovic however had a 3 slam season and only won1 the year after. So I can see how 2011 was the odd year for djokovic.
Nole def. Fed at WTF fair and square without any difficulty (that's in your head, btw, match is not over till it's over). Fed this, Fed that, uh oh ...
Without any difficulty?! You must be joking.