Djokovic had just turned 28 a few days before 2015 RG.
Federer was around 28 years 10 months at the time of 2010 RG, that's much closer to 29 years than 28 years. That's not altering their ages. that's looking at it realistically.
a 6 year difference in those respective slams is better way of looking at it.
if 15 djoker can't beat 15 stan, what makes you think he'd necessarily beat 09 fed ? just wishful thinking ?

Simiarly ........if 11 djoker couldn't beat 11 fed .......
yeah, a bleeding toenail in the 4th set (a minor hindrance) vs a sickness that affects over several days. yeah, great equivalence. are you for real ?