It's because he was really new and it was the first time that he fought in the US. Although Oscar that time has saw a lot of potential in Canelo that's why he brought him in the US and then fight Floyd during his best years. Canelo later admitted that Floyd is one of the best opponent he has face in his career and it's obvious that Floyd defense is very hard to crack. Gonna be hard to pull that one, Crawford is good but not as elite as Floyd. We have seen him hit by his last opponent at 154 lbs and he almost go down.
I don’t think even prime Canelo could’ve beaten prime Mayweather. Their styles are completely different, Canelo is strong and smart, but he doesn’t have the speed and movement that Mayweather had.
Mayweather was just on another level. If you look at his fights, even Pacquiao looked like an amateur against him. And sure, Pacman mentioned he had a shoulder injury at the time and wasn’t at 100%, but still, Mayweather controlled that fight from start to finish.