27?
Try 30+
He'll be at 25 in September already
We were alive and interested in the sport in this era so we can micro-analyse the reasons for this but the next generation won't know this.
History will be much kinder to Nole because he has all the factual achievements and records in Tennis.
The biggest thing Nole's domination in this period does is dramatically diminshes the greatness and legend of Federer and Nadal and I am not exaggerating.
This is why longevity is even more important in Tennis. It gives you the opportunity and the window of weak competition to dominate. Djokovic lasted this long and kept himself fit to pounce on the moment the other 2 decline and statpad Grand Slams for fun. Not saying he didn't win stuff when the other 2 were around; Djokovic is unbelievably good without any doubt.
Given his insane fitness regime, I can't see him stopping anytime soon.