You find room for the 6'9'' guy who runs well, has offensive moves, can shoot, defend, and block shots.
It's not a roll of the dice when you offer a kid like that; you know he's going to contribute...at the very least adding athleticism to a team in desperate need of it.
Neilson, Nixon, Shaw, Sharp, Calvert, Andrus...those are gambles. Best case, they're depth guys. Worst case, they eat up scholarships and cause roster logjams - making it impossible to sign late bloomers / JC boom-or-bust type players.