All of Robinson's troubles came against strong pressure fighters; LaMotta, Basilio, Fullmer, Basora, Turpin, etc; and Hagler normally went aggressive against taller, quicker fighters who didn't wanna engage. Like Jones - and Leonard - Robinson could use his speed and skills to win a close decision. But I think Hagler when fighting aggressive is all-wrong for Robinson. I also don't know how Robinson handles Hagler's jab.
I think Hagler's southpaw attack (and how Robinson responds) could be the deciding factor in this fight. Either it takes Robi out of his game, or it opens up more opportunities for him to tee off with his right hand.
Id favour Hagler. Was a better middleweight imo and styles seems to favour him (unless he uses the same strategy that he did against the other Sugar)