I initially thought of Monzon as considerably taller than Robby, but forgot that he only had half an inch on him. Robinson was a good deal taller than Leonard.
There's pics of Robby and Louis, and Robby doesn't look significantly shorter. He looks significantly SMALLER, as in Louis was a much bigger man... but Robinson was indeed tall.
Robinson could gain 20 lbs from the LaMotta VI fight (155 lbs) and he still wouldn't look fat (he was still a MW when Joey Maxim knocked him out for the LHW title due to exhaustion)
If Robinson were around in the last few decades, I think he would have been a dominant junior middleweight. We wouldn't be thinking of Hearns as the GOAT at 154. Junior middle was likely the ideal division for Robby.
I don't think Robinson would've ever peaked at 154. Moreover, his best weight to come in while at welterweight, was in his eyes, 144. He said that's where he felt snappiest, fastest and most mobile.
Lamotta VI is the best complete Robby performance on film, and he weighed 155. If he were around in 2022, he'd be on juice just like Canelo, Inoue, Usyk, Spence, Crawford, Fimo are. Combined with his frame, I think he could easily handle 154. But he could also be dominant at 147, it'd be up to him.
He himself felt he was better at a lighter weight, and also like all of those guys, he'd be able to rehydrate. He'd always be better at WW.
Robinson via decision. Monzón would make it rough and lump up Robinson pretty good. But I think Ray with his speed, movement, and quick combos would carry the day.
I dont think there's a wrong answer. Close to 50-50, but I do side with Robby. I think Robinson had the firepower to hurt Monzon.