I think it's a little early to be proclaiming what Hamilton's ceiling is. He was never a full-time baseball player in HS like a lot of these kids coming up now. He was a 3-sport kid with off-the-charts athleticism. He's just learning how to switch hit. While he's very skinny, he's also a six-footer, so there's a chance he'll add some strength to a frame that could leverage more power than folks see right now.
Lot of room for growth with this player, still. Goldstein is just being optimistic, not unreasonable.