Marv. Over 12 or 15. Too experienced, versatile, well-schooled. Just a different level of class. Nunn might give him a bit of a headache early on, but it wouldn't last once Hagler hit the groove.
I think that, in many rounds, Nunn could actually dominate here. When he got moving he was awkward, difficult to hit and had a hellacious set of punches with which to respond. I think Nunn is one of few boxers to have the footwork to really trouble Hagler and footwork is very important in a southpaw vs. southpaw match. The problem, however, is that Nunn was never able to sustain such skill and had too many moments on the ropes, covering up inside, trading etc. It's in those moments that Hagler would do the necessary damage and open up plenty of scoring opportunities in the later rounds. Over 12 I think Hagler wins a close but clear decision; over 15 I think he stops Nunn.
Hagler by late TKO. Nunn's speed and range would dominate the early rounds. However, in the end he is worn down by Marvin's aggression. Talented as Nunn was, if Toney can KO him, so can Hagler.
"You can run but you can't hide" would go well in this one. Nunn could be an absolute pain in the butt for Hagler but if we're taking any version of Hagler, Hagler wins. At his best, I don't think he will be frustrated long. He's going to rough Nunn up. Nunn is going to get tired and start running out of gas and if he didn't get knocked out, I think he'd take a pasting by the end of it. I do believe fifteen favors Hagler even more.
Nunn can outbox Hagler for as long as he can effectively use his range and keep moving, jabbing and throwing. If he try's to get in range too much like he did against Toney/Roldan Hagler will eat him up. Hagler for his part needs to pressure Nunn, work his body, pump his jab. I know the Hagler worshippers don't want to hear this but Nunn can outbox Hagler to a decision, although Hagler could well stop Nunn late on. Its a genuine 50-50
Nunn could give guys like Tate or Kalambay hell but Hagler was a different caliber. He would have made things really hard for Nunn and probably stopped him in the mid to late rounds or lopsided decision. Different caliber.
If this was the Marvin Hagler of the Ray Leonard fight, even John Mugabi, I think that Michael could outbox Marvin for an UD.But in a prime-for-prime scenario, expect to see Nunn to cruise out to an early lead, only to face a fierce Hagler by the sixth round on, by this time Hagler really starts to exert his authority, and by the eleventh or twelth round, Nunn is out of there, either by KO or TKO, KO most likely.