SRR was an all-time great champion no doubt. Sugar loss his title 4 time as champion. Robinson was the one who was overrated as a MW.
In my opinion Robinson would have boxed Hopkins from the outside and, whit his speed and accuracy, would have won the fight on points. But Sugar Ray should have taken a few good shots, he was the best at middleweight (and probably also p4p), but the Executioner was one of the best at middleweight and an ATG. In short, a tough opponent for everyone.
Robinson lost his title 3 times. The last time he was stripped. He retired once with the title in '52. He lost it to Turpin, regained it. He lost twice after he was well past his prime 130 fights into his career to Fullmer and Basillio.