Beterbiev vs Foster

Foster KO.

 

Those heavies were the size of today's light heavyweights and cruiserweight. Someone like Quarry or Folley could rehydrate to light heavyweight.

 

What rules do they fight under? Talking about the size of Beterbiev as if it’s a plus, it’s a minus if we use the same rules.
Same day weigh in? Foster pounds him into the ground like a nail at 175, size would be a disadvantage here.
Drain and rehydrate, maybe Foster is able to fight at 168? Imagine that, he could fight Canelo.
Each to his own era rules, Beterbiev can weigh in day before and come in closer to 185-190, and Foster has to weigh in same day at 175, one would favours Artur.
They are both outstanding fighters, but the rule changes have sort of arsed up any meaningful weight class based comparison. Almost need a before and after the weigh in stupidly era for rankings. I know I am being a bit of an ass about it but it would be more accurate to do h2h of this nature based on their fighting weights.