What I was getting to about homicide's post was the oversimplification of how things were. Most fights weren't 20 rounds. 45 was extremely rare.
Gloves might be 3 oz, but often were bigger in the late 1800s and early 1900s. Ring size was all over the place as well. 16 feet in one fight, 24 in another, and everything in between.
There were guys that move a round well and jabbed a lot. (Corbett, Tunney etc.)Frazier and Ali were past it when I started following boxing as a kid. Anyone who saw the Thrilla in Manila (among other fights) should know they were as tough as nails and would have been at the top in any era.
1- From the 1860s-1920s, championship matches were often 20-45 rounds or better. Some fights had no round limit at all but were fights to the finish where somebody either was knocked out or they quit. One only needs to look back on various records from that time frame and we'll see that most people in their first few fights were already dabbling in 10 or 15 round contests. Short matches of four rounds or six rounds or eight rounds were generally considered sparring matches. But it also depended on the jurisdiction you went to. People tend to forget but they were staging 20 round championship fights as late as Joe Louis. So I tend to disagree with you, fights were typically longer back then.
2- As for gloves from 1860s-1920s, you will see on many people's records that it will say "skintight gloves were used," which was coach driving gloves. It was really to the discretion of the fighters as to what they felt most comfortable wearing. There was no real uniformity with gloves until much later. Most of the gloves you see fighters posed with in photographs were not the fighting gloves but the sparring gloves. For a long time gloves were 3 oz with opposable thumbs and later on it became 6 oz with opposable thumbs, only for the gloves to get up to 8 oz with the thumb attached to the glove so people couldn't use it to thumb anyone or grab the hold of their opponent. As for rings, some were round and some were rectangular and some were squares. Most did not have wooden flooring but was fought on turf. Wouldn't be until much later having a universal consensus of a square, but they varied in sizes for a long, long time. For example Rocky Marciano fought Don Cockell in a 16 ft square ring. When was the last time you ever saw a world championship fought in a ring that small?
3- Yes, there was fighters who moved around well but if you notice they weren't throwing high volume jabs or quite frankly doing a lot of punches anyways. Body punching was more the emphasis in those times than it was in the time of Ali and Frazier where people were teeing off at the head more than ever. You had to really reserve your punches and be smart about when and where you were going to throw punches back then otherwise you risked breaking your hands. Which is why a lot of the fighters back then look so methodical and cautious on film, or they resorted to clinching so they could set up body punches or upper cuts.
That being said I think Joe Frazier would have had more success in those times than Muhammad Ali, especially the further back you go. He was more of a body puncher, and pretty rough and tumble when need be with great conditioning and a great chin. Ali, I think, would have busted his hands early and would have spent the majority of the time running around for 15 rounds burning himself out and that's when his opponents would have attacked him kind of like Jess Willard weathering the storm for 20 rounds only to come back to knock out Jack Johnson in the 26th. One might even make the argument that Muhammad Ali would have been penalized in those times for "not fighting like a man," relying so much on running away from opponents.
And lastly I might point out that Muhammad Ali once said in an interview with Howard Cosell when talking about how he would have fared against past heavyweight champions he was quick to say that he never would have fought in the bare knuckle era because he wouldn't have been pretty anymore. So this notion or idea that Muhammad Ali would have been the top man in every single era in boxing history is nothing but a flight of fancy.
I'm really hoping you're joking.
that's why everything I say is complete BS when it comes to boxing.