Hagler destroyes ketchel. While ketchel was a great puncher and while punching power is not relegated to any one particular era, skill set is. Hagler was too skilled a boxer/puncher who in all likelyhood was totally unlike any fighter that ketchel ever faced. Haglers granite like chin would have taken anything that landed and he would have took ketchel apart and knocked him out, probably in the mid rounds.
I have to go with the contained aggression of Hagler, I think he is versatile enough to keep Ketchel reaching for him ,but Stanley had natural raw power and he carried it up till the last bell ,if he landed,even Hagler's chin could be dented.
Ketchel supposedly had immense power, but Hagler was a fantastic all-rounder with possibly the best chin (bar Chuavlo) of all time. I say Hagler tears the brave and durable Ketchel to shreds by the 10th round. Under modern rules it probably gets stopped sooner.
Hagler would win due to his superior skill-set and his freakish durability. By decision. I do think that Ketchel would be able to hurt Hagler and would get Hagler's respect at some point. In a series of three I'm inclined to believe that Ketchel wins one.
haglers skills what come into this more than Ketchels power. Haglers chin was granite but he could be dropped in this fight because Ketchell was a beast but i doubt it. I think hagler can outbox him and i think he ould play it safe like against Duran and settle for a points victory over 15