The schoolwork thing does seem to be a problem, but not related to perfectionism. It sounds like he's not putting in any effort because he's not engaged, because it's far too easy. That may be the case in baseball or scouting, too, though it may also be that those activities contain too much routine.
This condition can lead to perfectionist tendencies in other areas.
Perfectionism doesn't have to manifest itself in all activities. It can just show up in the ones in which your DS thinks he should be perfect at. Like music. And math.
There's a whole different kind of pressure involved in performing by yourself versus in a group, and for family members versus strangers. I've known several performers who hated having their friends and family see their shows.
