Some people will always look to discredit wins and find excuses when none are there. Even if it was at 154, some would say that Canelo has already outgrown the weight and should be fighting at 160. He could have another few big victories behind him but people would say they were no preparation for Floyd (always a good excuse since there's no other fighter who has a comparable style married with his skill level). These fighters could also be retroactively be described as bums - they lost to Canelo, so they must be!

Unless Canelo comes into the ring looking like Oscar v Pac, Floyd will get lots of credit for beating him, especially if it's decisive. The people who won't give him credit would never give him any under any circumstances anyway.