The champion and #1 contender versions of Walcott, Moore, Charles and even Louis did though. Everyone of them were leading contender or champion in their own right when they fought Rocky. Did you read those links I posted? Johansson said Rocky would "knock out Liston very quickly". Knowing he would not get a 4th fight with Floyd, before the first Liston vs Patterson fight Ingo said "If Liston wins its good for me, I would like to fight him"
None of them were prime in any of those fights and Ingo refused to fight Liston whatever he claimed , despite being offered a million dollars to do so ,[2 million in1963], its a matter of public record.
In August 1962 Ingo wanted to fight Liston. He studied Liston and saw flaws. He even used marciano as an example from what he learned "oh Rocky would knock him out very quickly". Whilst Ingo admired the Liston jab Johansson felt that Sonny was too used to coming in, that too much of his speed depended on the opponent letting him set off first. "Don't let him come in, he's coming all the way in and that is giving him more speed than he has, he's always starting before the other fellow. Patterson must not let him start" he thought Liston could tire very fast if somebody set the pace and started first "because he is used to always coming in. That's what makes him look good and makes the others look tired. If somebody does it to him he will be the one getting tired" When was this offer declined?? In 1963 wasn't Sonny contracted to rematch Patterson?
In their first fight Frazier hit Ali on the way in all night. The hook that put Ali down was not close range. Joe overcame an 82" reach. A longer reach than Foreman had. Probably because he could see better back when Joe fought Ali.