He is getting old and clearly slipping. His punches don't seem to be as fluid and his s jab went from a firing piston to a paw/polearm. He should fight Fury and Wilder then retire.
Go on youtube and watch his training sessions on the mitts for his fight with Jennings,you will quickly change your mind.
Look at Vitali's training clips, he looks like a monster also....doesn't translate into an actual fight though. Of course he's slipping, he's coming up on 40 yrs old, he doesn't have the quickness he once did.