It's no well-kept secret that Hayes is known for his defensive prowess. At 6'6", he's grossly undersized for a center. The problem for most centers (and athletes in general) is that they don't move their feet quickly enough to keep up with their competition.
This video is a perfect example of how Hayes has been able to guard talented offensive players like Amar'e Stoudemire. Keep in mind that when you play against a team like the Knicks, the goal is not to stop Carmelo or Amar'e from scoring. For most teams, the goal is to keep them from creating shots for others and, thus, to shut down everyone else on the floor.
(The Kings play the Knicks on New Year's Eve and again in February, and I'm looking forward to watching Hayes attempt to guard Amar'e now that the Knicks have another scoring threat in Carmelo. There's a solid chance he won't succeed, but you know he'll be trying).
What was Michael Jordan's biggest asset? Probably his penchant for competition (no, gambling does not count). Where did this asset present itself most abundantly? When he D'd someone up and shut them down for the entirety of a game.
I am by no means comparing Jordan's defensive skills with Hayes' abilities. On the other hand, there is something to be said for a player that always defends the best player on the other side. If nothing else, Tyreke Evans will no longer have to constantly take bullets for the Kings in this regard.
Bruce Bowen and Shane Battier have long been known for their abilities to play defensively, and if Hayes sticks around long enough and figures out how to shoot a free throw (60 percent in his career), he just may be remembered alongside those two names.
OK, fine, there's no way we'll remember him like we do Bowen—but you get the point.
Who we MIGHT compare Hayes to sooner rather than later is Sir Charles himself, Charles Barkley.
Barkley played 16 seasons, averaged less than 10 boards per game ONLY in his rookie season (and averaged a total of four offensive boards per game, which is straight up insane, given his height), and managed to drop over 22 ppg.
Hayes will never get close to that. But guess what? Barkley had the exact same tiny 6'6" stature as Hayes.