JD's ability to score in the halfcourt will determine what level of NBA player he will be, but as of right now I think he'll have a place long term in the league.
Juhann might be ready to contribute and develop right now.
Kabengele is good on the offensive end finishing plays, but I feel like he's constantly late rotating and always far down in the drop. Not sure he'll fit in with what the Celtics are trying to do.