I don't think Cormier ever came into his true potential or presented his best on stage. 99 was probably the closest. He should never be beaten by guys like Cutler ever, or even Dexter for the matter.
There is a reason why Dorian spoke the way he did about Chris.
That being said, we will never know as I think it's too late now, Chris is in his forties and the competition is a lot tighter now. But if Chris presented his BEST he would wipe the floor with Heath, Kai, Cutler, Dexter, Branch, etc...