Djokovic had significant H-H advantages over Nadal and still peak Federer in 11, which makes Novak's 11 superior to Federer's 06, due to competition.Djoko's 2011 was better than 2015 because competition was much weaker in 2015. Either way there a few other seasons that are more impressive than both Fed 06 and DJoko 11.
McEnroe 84 for example.