That man was NOT 180 lbs during the Khan fight. I don't know where you all keep getting that number from, but that dude's never stepped in the rign that heavy.
There are weight classes for a reason...height, reach, neck size, walk-around weight, etc. Just because a guy rehydrates to a certain size or walks around a certain weight between fights, doesn't necessarily mean he can compete at that weight.
Kovalev probably walks around at 190-195 lbs and gets hit by guys around that same weight who rehydrates to about 185 or 190 on fight night. Canelo doesn't face guys of that size...and the Chavez Jr. fight doesn't count. Lol
You're absolutely correct it was 187