You could be right. It all depends on how much his reflexes have slowed. He hasn't taken the kind of punishment throughout his career to be the average 40 year old fighter, but not even that can control the reflexes slowing down.
Once he hits the point where he sees what's coming, but can no longer get away from it, he's beatable. Then a guy like Canelo could get him on the ropes and wear him out.