The Robinson of Valentines would whup the Duran of the Hagler fight. At welter it would be a much better fight.
Turpin was a beast albeit for a short period of time. He was a big Middleweight, very strong, awkward with speed. I would say Hearns would give Robinson some things to think about.
Robinson could be lured into a streetlight with Duran but he may also knock Duran out. It wouldn't be the smartest way to go but Robinson 1 punch power in each hand.
I can’t see Duran troubling Robinson- I think it would be suicidal for Duran to fight anything like himself against Robinson.
Turpin is one of those guys most on this site hear the name, they check box rec or some other source that doesn't give a complete picture, and automatically assumes he'd lose to Hagler. They never take the time to actually watch him fight other than highlights of his fights with Robinson (Which if they take the time to actually watch those fights not just highlights it shows how good he could've been without the personal demons.) Turpin was one of those awkward guys that I could see giving Hagler fits in a 1 fight situation. His unorthodox movement, ability to counter quickly, quick hands and power could surprise. Unlike most of the historically great middleweights in history whom were typically go forward puncher types with great power like FLowers, Zale, Walker, Greb, or Tiger who's styles played into Hagler's strength, Turpin style wouldn't . That's where I could see him giving Hagler serious issues in a one fight situation. Changing the subject a little There's a great documentary on Turpin I saw years ago called "64 Day Hero". If some haven't seen it, watch it, it gives great insight to who he was.