As of right now, he seems like he is not prepared to be a part of the Celtics' long term plans. He lacks athleticism, and does not shoot weel enough away from the hoop.
I think the athleticism is unlikely to improve. He has short arms, and would need to develop a degree of lateral quickness that seems unreasonable, given the circumstances.
However - what if she shot 40% or better from beyond the three point line? That's a skill he could legitimately improve. It would take a power forward away from the basket (if he could do it) and would open up driving lanes for Rondo. It would also create some serious dynamism in terms of pick and roll, or double pick and roll plays, where the big man could screen out beyond the three point line.
Would you consider him a part of the Celtics' long term plans if he could improve his percentage from deep to that degree? Channing Frye presently shoots 40% from deep, and is 25th in the NBA in 3PFG%, by way of comparison. Kyle Korver is 1st at 47% (which is INSANE).
To what degree would he need to improve his 3P shooting to be a part of the C's plans (if you don't think he already should be)?