At 23, if he wants to have anybshot at being drafted he has to put his name in this year. Anything short of being National POY next season will make it hard for him to be drafted as he will be even older.
Aluma is in his 4th year of college. He very likely already has a degree, so the argument he should return for academic reasons is moot.
It simply boils down to this. If he meets with a bunch of teams and even one of them says "hey we will take you in the 2nd round" he has to leave. HAS to...he wont get that opportunity again.
If you care about Keve more than you care about VT (which im sure MY does) thatll be pretty easy to understand, but Im certain that wont be the case for some.