I don't think McCallum was fast enough. That's not to say he didn't have the timing, but I think Hearns can make it a boxing match and take a decision.
McCallum isn't strong enough or athletic enough to beat Hearns. He wasn't aggressive or fast to land and chase him down. It probably would be a boring fight. Hearns jabbing and moving and McCallum slowly pursueing and trying to counter. Hearns by MD
No one would be able to beat McCallum at this weight unless it's either Hearns or Winky Wright. Could go either way but I'm confident in thinking that Mike would have found his mark in the later rounds. Don't think Mike would have been able to outbox Hearns, but he can KO him, much like he did against Curry.
McCallum had the makings of a guy who could give Tommy all kinds of trouble, especially at that weight class. Tough defense, solid chin, good power, vicious body attack. I think he wins via stoppage or KO sometime late.
Over 15, I'd go with Mike. He didn't have Leonard's speed and power, but he would just not pressure in spurts like Ray did. He'd work steadily behind the jab looking for those body shots. It would take him a couple of rounds more to find the mark with body shots than it did against McCrory, but once he does I think the result is the same.
