If no one has thrown a lot of punches, I will

Their KO ratio above their original weight class is almost identical. FYI. If you look at their overall KO numbers, JMM has a slight advantage, but certainly not enough to make the comparison ridiculous.

At Mayweather's original weight class, he had a 76% KO rate. That's good power. Fighting guys who outweigh you by 15+ pounds will lower your KO rate. Both JMM and Floyd are in the low 30% in KO rate after their original weight class.