Kinda works both ways though. Thompson was 40 years of age with a lot of mileage. Bellews was past prime too, as were John Ruiz, Nikolay Valuev, Audrey Harrison and practically everyone Haye fought at heavyweight. Derick Chisora might actually be his best win. So which fights at heavyweight lead you to believe that Haye was better in that class than Povetkin ? Was it Mark Dimori ?
I generally bracket a fighter’s prime and don’t downgrade a fighter by very much for things outside of that window, assuming it’s a real prime and not a “Tokyo Douglas” one. His best win was Valuev. I don’t know that he’d beat Povetkin because he was overly gunshy in many fights. It’s his fight to lose though.