Agassi reached the final of the US open in 2005 while Nalbandian lost in straight sets, Roddick lost in the 1st round. Why ? At that time 35 year old was like 39 now, yet he is reaching farther than Fed's main rivals... ?
Regarding Djokodal dominating 10+, even Fed did dominate guys 10 years younger like Dimitrov/Raonic and others from that early 90s age group, whats so surprising if Novak'Rafa have their own dominant run since all 3 are GOATs so they are expected to dominate upto 10-11 years? Djokovic is in supreme fitness even at 34-35, he can tire out guys like Tsitsipas/Medvedev who are much younger to him, credit to him.