ideal upside (extreme optimism): a shorter, faster Joe Dumars. solid D, solid jumper, good character guy and smart player.
Worst case: Gabe Pruitt. a player that rarely gets off the bench, shows a little promise here and there and then ends up out of the league in 3 years.
Probable case: He'll be unique. He'll be fast like Rondo, play solid D like Rondo, shoot better than Rondo but pass/ballhandle worse than Rondo. hopefully end up shooting FTs better than Rondo.
If he shows as much promise as hyped, I could see him either being the first guard off the bench in the post-big-3 era or Ray's replacement while Danny tries to get a bigger starting SG.
I anticipate little to no playing time this year. If he sees the court outside of garbage time it'll either be because he's outplaying even the most hyped expectations and Doc can't justify sitting him (which would be fantastic) OR Danny has botched the bench rebuild and he has to play due to backcourt injuries to Rondo/Ray/Nate and we witness the usual rookie growing pains (which would suck).