Leonard "orchestrated" some fights at MW, SMW & LtHvy in order to gain some additional titles. Lets put him under the "old days" methods and have him move up in weight as Welterweight Champ and try to take the title from MW Champ Harry Greb. Is it Robinson-Lamotta, or Greb-Walker all over?
I strongly suspect that Ray Leonard would get the beating of his life from Greb at 160. Greb sure as hell wouldn't stand off and box Leonard like Marvin -he'd swarm all over him. The hell that Duran, with his LW frame, gave Leonard would be multiplied... Stoppage? Over 15 -I'd guess yes.
If Leonard boxes, he may get simply swarmed on, if he fights, which he will because he was an offensive minded type of boxer, he just wont be stromf enough. I wish i could have seen Greb because id be able to analyse things like defensive lapses or faults that may spell bad things for something that Leonard did well. Given the styles matchup though, this may not be a factor. I'll pick Greb as it seems logical.
It's hard to say what your dealing with when you say 'Harry Greb'...Is he a similar, but more rugged version of Cerdan? Would he present the picture in the ring of the unorthadoxy of a Calzaghe? With a physical mugging style? But the records shouts at you, and the film of opponents like Loughran, Walker, and Tunney gets your attention as well...Greb by decision. Stoppage? No way! Much lesser fighters than Leonard (IMO) went the distance with Greb.
Leonard. More tested in a better skilled division (and era) and had the better tools and arsenal. Greb was great in his own time and i rank him pretty highly on an all time great status, however Ray would simply be too much. I look at the time Greb fought to as being before boxing hit its true stride. He didn't have a style that was ahead of his time unlike Jack Johnson, Ray Robinson ect.
