Ultimately it should be his decision - but if I were his dad, given that he is not signed and if asked, I'd suggest skipping basketball and getting ready for a great spring.
Basketball season overlaps with baseball season - and the conditioning he should be doing as a pitcher to prepare for this season won't be a part of his basketball routine (other than having great legs!!!)
Another consideration is that he may want to make some unofficial college visits this winter - and if he is in season, skipping weekends to visit a college is probably not what the basketball coach has in mind.
So, if it were my son, I'd be suggesting hitting the gym and going to visit a few of the colleges that he has already applied to. Even an unofficial visit show interest - he can meet the coach and potentially kick off some additional dialog.
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