They actually fought, Muhammad Ali vs Buster Mathis Sr on Nov 17 1971 in Houston, Texas, Ali won a unanimous 12 round decision. the undercard was George Chuvalo vs Cleveland Big Cat Williams. I heard the fight over the radio. On the Saturday following the bout on ABC's Wide World Of Sports was airing a replay of the bout, they were playing old rock and roll songs like I Want To Hold Your Hand by The Beatles to the fight.
Muhammad Ali called out Buster Mathis Sr and Thad Spencer after he dispatched Zora Folley in the 7th round of his last title defense on March 22 1967 in Madison Square Garden, when asked by commentator Don Dunphy who would be next, Angelo Dundee responded, Eduardo Corletti could be next. Ali would not fight again for 43 months as he refused to accept the step forward and be drafted into the U.S. Army, he was stripped of his title and boxing license.
He was not much older-unless he had some hormonal problem, the slight difference in how tough it was to stay in shape a bit later in the 1970's easily could have been offset by training slight harder. Instead he did the opposite. It is telling when muscle is lost-while you may add fat, if you are still active & doing the same things, homeostasis should enable to to maintain it without much effort-waaay past your mid-30's. Maintenance of strength & muscle is relatively easy.
I never knew that, that he'd been out of the ring for about two years. Definitely won't have helped him at all, having ring rust too.
Mathis was supposed to fight Blue Lewis in 1969 but he walked out on his training camp and disappeared from boxing for about a year and a half. He'd spent most of 1971 trying to get a comeback underway - fights were planned against decent but beatable opponents like Tony Doyle and Jack O'Halloran - but he had trouble getting licensed because of that breach of contract against Lewis.
He gave a decent account of himself early when he was fresh but by round 5 Joe Frazier was having fun with him. Maybe it was Buster's wheezing that let Joe know he was gonna be the champion that nite. Frazier more or less punished him for those amateur decisions.