Let's just see how Djokovic does in his 30s.
Federer had a 6 years prime (slightly more, TMC 03 - AO 10), Nadal had an about six years prime (clay season 08 - clay season 14), 2017 should be interesting for Djokovic - it would be monumental if he manages to extend his prime, though.
I don't like holding pre/post-prime losses in as high esteem as prime losses.
The reason Djokovic bad losses are given so much flak by some is that they happen right during his prime/peak. Giving significance to the numerous bad losses of pre-2011 Djokovic is silly, although real haters don't seem to know that, but why bother? Just screw 'em.