i just mean when you are fighting in the same weight class, you either are the right size and got the right amount of muscle and in great shape or you are super tall and skinny or you are just fat and fighting in a higher weight class. So ceteris paribus, more muscle means you are short for your division which means you are like a Sean Sherk and you have weaknesses like striking do to limited range and mobility.
Having muscles like, i dont know Vitor when he was looking good vs someone like MArius Pudzianowski who can barely throw a punch cause his own lats get in the way.
Too much muscle is not efficient assuming you are in the same weight class as your opponent.