Size and weight matters when the skill gap is relatively equal. The skill gap here is huge. Canelo would dominate a young cruiserweight boxer with no real experience. The skill gap would be too huge.

I've had my ass handed to me doing some sparring with some clubmates 20kg lighter than me who are far far far more skilled than I could ever hope to be.

They pick shots better find gaps better t off faster dodge faster. It doesn't matter they are simply too good to even let me tie them up.

The only way Floyd loses this fight is if he chooses to. If height and weight were everything Valuev would not have lost to Haye. In fact the gentle giant would have been one of the best boxers in history.

I'm not trying to say weight isn't important if it wasn't rehydration wouldn't be a thing. I think you are just over estimating how much it matters with a skill gap this wide.