What evidence is there that Frazier faded from 1971 to 1973?

He didn't fight any decent fighters.
There's zero evidence that he retained his ability.

 

If you have to ask...

 

He'd climbed his personal Everest. I don't blame him for losing a bit of motivation after FOTC. Where do you go from there?

 

Inactivity after his fight with Ali. His fighting weight went up about 10 lbs. and testimony from Eddie Futch via Kenny Norton that Joe had lost his "drive" in training for Foreman.

 

Ron Stander.

 

I think he had health issues too.
High blood pressure.
Partially sited in one eye.
And Joe liked a drink !
I think by this point he felt he'd earned it.

 

There was a clear disenable change to any who had followed Joe's career. His body no longer seemed to have the steel in it, his speed in punch and moving forward was less, and the fire/smoke wasn't boiling over anymore. The Joe Bugner bout is a good example, Joe fought at a slow sparring pace the entire bout and didn't appear to be holding back, its the way he was physically then. When he nailed Bugner with the left hook that dropped him he held the follow up punch that may have finished it as he slowly went down. It was no longer the old smoking Joe.