Looks like he just got rid of the thinning, receeding, male patterened baldness at the front of his head. Probably just got tired of maintaining it, and / or stressing about it. Accept it, and move on I guess.
He's gotta shave that man, people don't even remember that MJ once had hair. So many players (even with hair) shave their heads anyway so it wouldn't be that bad but right now he is bordering george costanza territory