Aside from lacking self-confidence on his basketball abilities, I do sense he is not really that passionate with the sport. Because even if you are not that talented but you have the desire and is willing to make sacrifice to improve one's game, then we could say he might have a future since he is 6'9.
As of now, At best he is more like Raymond Lacson but at worst he could be a Raul Dillo. Right now he is trying but he seems bothered with his development. In fairness Isaac is better off than another prospect we tried to get 1 or 2 years ago, Thadz do you remember that 6'8 guy in Cali who we tried to contact via Myspace who rather go rapping and hip-hop than play basketball. He even had a video breakdancing hahaha
If Holstein could at least be a Bonnie de Jesus, we could take a gamble and just be patient and work on his game.