Bol Bol is worth taking a look at. There is potential there. But he has to get better, stronger, and so on by himself, in practice, summer league, off season, possibly G-League. NBA teams can't afford to give minutes to players like this just in the hope that they get better.
It definitely makes it tough for a player like Bol to "develop" but that is the way it is. When he is ready for NBA minutes, he will get NBA minutes. Right now, he is not quite there. Without improvement, all he is going to see is garbage time minutes.
These other non-drafted players that got over the hump did it because they got better and proved themselves. Took advantage of opportunities. No one developed them. They simply did it. Got opportunities and took advantage.
I am not sure if after this season if he should get a roster spot or a 2-way or what but there is potential there. He has to do the work though, show something in summer league, make the team out of preseason. He is 22 so he will get better. I am not sure how much more he will develop (fill out) physically though. It may not be in his genes.