Again, you seem to be slow here, no rules were changed if these fights were officially considered Middleweight fights. If they changed the weight limit altogether, then sure the rules were changed, but they played by the rules otherwise the Middleweight title wasn't going to be on the line. As far as playing by the rules to their advantage is concerned, that's what all fighters do once they make it big. Either through catchweights, venue, more money, gloves, referee, judges...etc, this will always be an issue and fighters accept it to get the payday and make it big. It's sad, but that's how it goes. In the end, Alvarez didn't ask Golovkin to meet any Catchweight requirements.