The limited film I've seen of him, he looks taller than the 6-8 or 6-9 he's listed. Also, although thin, he has the frame to add a ton of weight. And has extremely long arms. His body really reminds me of Anthony Davis, not that he's anywhere close to that level of a prospect, but he has the same body type.
FYI, no one knew who Anthony Davis was before his senior year either, he was a late bloomer who ended up being the #1 player in the country.
He might look taller because most of the guys he's up against are around 6'3"-6'5".
Also, going back to seeing him play, both games that I watched he brought the ball up on a break after a rebound and dribbled the ball behind his back on the way up. I know, kinda flashy, but pretty impressive for his size.