Joe is one of the few modern-day fighters/HWs that I think would have a good go as a bare-knuckle prizefighter of years gone by ... Ali? Sorry, no way. There was always just a grit and determination to the way Frazier fought that would have made him a serious prospect in any era.
Probably as much as any fighter in history but, even so, I agree that the thought of him in bare knuckle fights doesn't come easy. Whereas Joe just oozed the toughness and meanness I imagine bare knuckle boxers had.
I genuinely struggle to work out which gloved fighters, would have been likely to be good bare knuckle boxers. Endurance was obviously important, as was determination. It seems to have been next to impossible to score a quick knockout, against somebody who was willing to spoil. This makes me question whether power, finishing ability, and even having a good chin, were big game changers!
Maybe I could've chosen my words a bit more carefully, but if had to quantify it, I'd say: if money weren't involved, I don't think Ali would have been a fighter. He certainly had pride, determination and skill and will - but there's that indefinable quality that separates someone who boxes and someone who fights. The best example I can think of is that dustup that happened in studio when Ali and Frazier were commenting on their first fight for ABC, and Joe got p*ssed enough to start a scuffle with Muhammad. Ali wanted no part of it; Frazier was ready to break him in two and had to be pulled off him. Outside of the ring, I don't think Ali was a fighter - I think Frazier would always be ready to brawl, gloves or not. Just my .02 -