Between IT's expiring contract, his injury, his low annual salary and his greater value on the Celtics due to his free agent attacting presence, I don't see any way he can be traded while getting back fair value. If you trade an All-NBA player, 2 time All-Star, top 3 scorer in the league you had best be getting a player that is at that level or will grow to that level.
As has been said, at the moment the perfect IT trade is to not do an IT trade.