Good questions and people can always criticise any fight if they are inclined and looked hard enough.

All I can say is that Max did not lose to anyone else in between beating and losing to Joe Louis so think he was not that far from his peak at 33 years of age. I never understood why Schmeling did not get the world title shot after he beat undefeated Joe which was only 2 years earlier.

I think X meant Jack Johnson beating the first great white hope and causing race riots across the US was a great win.

Ali was not past his prime going into the first Frazier fight as he had great wins after that fight. Although it could be argued that he was not seasoned/active enough to beat Joe the first time after the ban from the sport.

Mike Tyson career peaked before Douglas when he was with Kevin Rooney. He went downhill after that losing his discipline, desire and spirit. Problems with management, marriage and promoters took their toll on his career and he looked poor against Buster.