I’m not one who believes that modern fighters are better than the black and white era but when you go so far back where you’re talking about Sullivan, I can’t help but think that the lack of footage transforms these guys into mythical beings. Harry Greb certainly has benefited from that. We know he was a monster but we literally can’t compare him to anyone without footage.
Even casual MMA fans understand Royce Gracie wasn’t the best and can’t be compared to the modern era of MMA. It’s an error to think that Sullivan had the skills and tools of people with over one hundred years of experience and a large opening up of the talent pool.
I agree that fighters have indeed progressed, as all athletes have, and will continue to do so. This is why perspective and looking at fighters thru their time is important. I think Frazier would likely get dominated by prime Lewis, Klit, Wilder and Tyson Fury, just as Bob Cousy would be tooled by high level high school players today. A guy like Lewis beat everyone he ever faced, something Ali did aside from his last two fights, he also did it against bigger/badder/modern heavyweights, lost less, but many would scoff if you dared said Lewis was on Ali's level. Gene Tunney also beat everyone he ever faced, and had an amazing 79-1 record, but again, many would scoff if one dared compared Tunney to Ali.
What we do know of John L is his incredible record, and we also have data from that time on how the fights played out. He was the baddest man in the world and untouchable in his prime, was 47-0 bareknuckle and only lost one fight, to champion James Corbett, after being off for years and coming back for a big pay day with gloves - still took Gentleman Jim 21 bleeding rounds to put Geezer John away. Either you look at things thru the lens of time and Ali is not the best/most dominant, or you do not look at them thru the lens of time and there are probably a bunch of modern fighters that would be better.
When I think of Jordan, I think of almost a prime RJJ type level of dominance, just clowning and demolishing guys, never losing an exchange type of situation. Many of Ali's fights were close and he took alot of damage, looked mortal alot of the time, fought tooth and nail and was by no means some steam rolling machine. His heart, chin and ability to bounce back from defeat was what made him special, but more than anything, the reason we speak his name in such reverence is because of his impact as a cultural and civil rights figure. Lewis, Holmes, Liston, RJJ, Sugar Ray Robinson, Pernell, Tunney, Dempsey, Greb, etc were not the charismatic civil rights icons that Ali was, and as such, they often get over looked compared to Ali.