It's still quite reasonable since they're only separated by 1 weight class and 4 pounds. Floyd would have conceded to a 128 pound CW to get it done, but Hamed knew he had no shot.
1. Castillo is bigger. 2. Castillo is a pressure fighter. Floyd doesn't like to be pressured. Hamed is not a pressure fighter.
I don't know about the catchweight though. Going down in weight is dangerous. And Mayweather could only even make 130 very early in his career. Whenever you have to drain down to an unnatural size that can backfire. I only think of this fight at 130 so that we don't have to think about Mayweather being drained.
That corkscrew right uppercut followed by a straight left from the prince would have had mayweather flat on his back, dribbling snot, blood and ****.
The reason he got so outclassed by Barrera was he's too unorthodox. Hamed stands no chance against a great and we'll schooled boxer.
Either way, Hamed would have been whooped.. just look what Barerra did 3 months later after Floyd called him out...lol