Pac,Juan,and other fighters could not put away Juan,but Kosta can? http://www.youtube.com/watch?v=asMX2POKPs0 We also forget Kosta could not go 12 rounds with Hatton and quit on his stool..
Tszyu had a stylistic weakness to pressure fighters with iron chins, but his accurate, power punching, sniping style matches up much better against Marquez. Both are great fighters, both have superb timing and placement, but I'm giving the nod towards Tszyu in this one.
Can Tszyu even make 140 anymore? If so he ought to still at least have one tuneup before Marquez, otherwise he would be just a bit too rusty to make this competitive.
Perhaps iron is a bit generous, but he had a very solid chin until his negligence out of the ring and punishment in it caught up to him. You can't make it as a pressure fighter to the world level without having above average punch resistance.
I do remember some of Kosta Tyszu fights. One of them Julio Cesar Chavez, I think Tyszu knocked him out in the later rounds. I don't remember if that was the first time Chavez got knocked out or not. If in fact he did get knocked out. Chavez was getting towards the end of his career but was still one hell of a fighter. Chavez was not older than Mayweather when that happened so maybe he was still at the top of his game but just could not get pass Tyszu.
A prime Tszyu would be too much for pretty much any 140 fighter. He loved fighting guys who box or were southpaws. The only trouble he ever had was with brawlers.
You know, there is quite a lot of middle ground between having the power to bomb JMM out and being Juan Diaz...
By pretty good version, you mean a year lay off ,over 35, and two major surgeries. Plus with a blind ref? KT must of been in his prime. Tszyu would of never got own end like JMM did against Mayweather. Even when he was stopped it still was a fight. Not a schooling.