It is evident that there is a common age for fighter prime but, no guarantee as it is very much so individual. Likely, tied to aesthetics and genetics. I agree that not everyone peaks or declines at the sametime as you noted above.
The problem I have is, Fedor went on a bender of can crushing, on ducking UFC, on ducking Reem x2 (if you want the link, BJ PEN DOT COM) followed by the 3 fight losing streak including a MW punching him rd 1 Said MW has a 9-12 UFC record on TRT.
Finally, Fedor excused his ducking Reem twice because of Steroids/PEDs/GEAR yet, he then fights TRT BF, and Hendo with his absurd elevation of test. This is flawed logic. What he thought was that, he would easily beat these fighters who finished him excusing Reem ducking who at the time, never tested positive (correct me here if I am wrong).
Fedor vs Reem was the only fight I cared for in SF. Given Fedor power punching and Reem's suspect chin at best, there is no excuse for this fight not happening. How many fighters did Fedor fight who used PEDs? Used more then once?