Hopkins was not in his prime for the second Jones fight, he was Remarkably good for his age and the amount of fights he had, but if he’d had to fight a younger version of himself he would have been toast. Same with Foreman in the 90s. Incredible comeback, he did clever things to adapt to his age and was a physical freak to begin with, but let’s not be silly. Tarver is fair enough I guess, but he didn’t really start fighting top pros or even going proper rounds until he was in his 30s. Donaire fought in the wrong weight classes for years is my opinion on that, he’s not better than ever, just still very good and he didn’t give up size last time out. It was still a freak injury to his opponent to boot, if that didn’t happen and he’d lost you’d probably be calling for him to retire.
It can be tricky to say for sure when a very talented fighter doesn’t fight top guys during the peak of their ability, but a guys physical prime is almost always when they are the best.