You know, anyone that has not read Adam's book on Sullivan really should. There is extensive, first hand newspaper coverage which is the best we have to go on. In addition, we have first hand accounts from legendary fighters we have come to know and respect like Joe Choynski who said Sullivan was a much bigger puncher than he ever was. I truly believe Sullivan was a natural wonder. Exceptional strength, stamina, speed and power. He was flattening men in an age when KO's were not nearly as common. The most amazing aspect was that he was self trained, never having the benefits of a Futch or a Blackburn. Can you imagine if that talent was properly harnessed ? He might have been the best cruiserweight that ever lived. Corbett is also greatly underated today. First off he was a large, strong lightning fast physical specimen. Watching him at 60 next to Gene Tunney was very educational. Corbett's career is clearly broken into two chapters, pre and post title. Post title victory career was never the same. The conditioning, the dedication was over. That being said, on his prime, say 1890 to 1892, he was exceptional . Prime for prime, who knows. The ring size and the fight distance would be major considerations. The larger the ring and the longer the distance, the better the shot Corbett would have. However in a 15 round fight, prime for prime I truly like Sullivan.
I don't quite buy the logic. Sullivan matched up prety well with technical boxers from what I can see. This type of fighter made up a lot of the contenders during his prime and he was typicaly walking them down and stopping them inside four rounds. I think that there is a stronger case for a prime Jack Dempsey loosing to a prime Gene Tunney than for a prime John L Sullivan loosing to aprime Jim Corbett.