He was clearly one of the great heavyweights of his era. That’s not in question. But declaring him to be the greatest seems like too much to me.
[By coincidence I had been watching some of his great fights (i.e. Frazier I & III, and the Foreman fight) a couple of months ago, and this thought occurred to me then, but it became more topical with his passing.]
If you look at his record against some of the other top heavyweights of his era he won more than he lost. However:
[ul]
[li]He seemed to cheat a lot. Most notably, he would consistently, when in close quarters and/or leaning on the ropes, to reach an arm around the back of his opponent’s head and press down on his head/neck. This kind of thing is wearying for the opponent, and as Ali won most of his major fights by attrition has to have been a major factor in his victories. For some reason the refs rarely if ever called him on this. (The ringside announcers commented that “he’s getting away with it”.) In addition, there have been allegations that the ropes were deliberately loosened in the Foreman fight, which allowed Ali to lean his upper body further away from Foreman. Whether or not Ali’s people loosened them, they were clearly looser than the standard, and this played into his strategy.[/li][li]His W-L record was enhanced by a lot of close calls and questionable decisions (e.g. the Norton fight decisions, the stoppage of the Foreman fight, Frazier’s guy throwing in the towel when Ali himself was ready to quit). (Leaving aside allegations that Liston might have thrown one or both fights.) While winning the close ones is sometimes the mark of a champion, this is less true of boxing than of other sports, since boxing depends a lot on judges’ decisions.[/li][/ul]
If you compare his record against Norton and Frazier - 4-2 record in 6 hard fought battles with some questionable decisions thrown in - compared to Foreman’s record - 4-0 with 4 dominating performances - ISTM that you could argue that Foreman was the better of the two, head-to-head notwithstanding. As above, Ali used devious techniques, benefited from a questionable stoppage, and - per Wikipedia - refused to fight Foreman thereafter, which does not suggest he had a whole lot confidence he could pull it off again.