I think it's because his KO% was 60%... No I think it's more because he lost a lot of his power in the 70s as his hands declined. That's the version of him people remember nowadays He also rarely stopped people with one punch.
In his prime years, 1964-1967, Muhammad Ali's challengers, had never seen that kind of speed in a heavyweight fighter and were befuddled by his style. He stopped 7 of 9 of his challengers, only George Chuvalo and Ernie Terrell went the distance with Ali. When he returned in 1970 from his enforced ban from boxing due, to his Draft Evasion conviction, in 1967, his attributes were gone, He could not dance non stop for 15 rounds, and spent the majority time laying on the ropes, became more vulnerable. The only thing that changed was that he did punch harder and had to think of new ideas to defeat his adversaries. He did suffer more damage, an example, the broken jaw against Ken Norton, on March 31 1973. His neurological issues began to surface due to his lack of prime mobility. He took more hits from his opponents, something that never happened in his first reign as champion.
When Ali wanted to he could hit very hard. It's just that with his style, and delicate hands, he usually chose to peckh and poke his way to a safe points win.
The knockout rate is somewhat distorted by the fact that Ali stopped his career much too late. He does not impose any KO on his last seven fights. But if we take his record after Norton in 76 he was 69% knockout, which is already very good in view of his opposition.
He could punch a little. Foreman described how he would time you and hit you coming in to use your own force against you. Not an elite puncher, though, by any means. Speed, early on, and later chin and intelligence were much more a part of his game.
Ali was a better puncher earlier in his career but it’s well known he had right hand problems and it prevented him from throwing with more authority. His most famous fights came in the second half of his career
So basically you've got a fighter with **** offensive capabilities and clearly such **** defence he ended up with brain damage. Best of both worlds, the greatest ever!
If Ali set down on his shots he could hit pretty hard. look at the photos of him turning over right hands and catching Foreman flush! One of the underestimated aspects of his win over George was how often he was nailing George with big right hands.