Lets say Hagler's career mirrors Briscoe's. He faces every single opponent that Briscoe did, in the order Bennie did. How does Hagler fare? How much better is his record than Bennie's? Against Monzon twice? Valdez three times? And so on.
Marvin would take a couple losses early on but with so many tools would take control of the division and beating all comers. ALL comers, bar none.