Simply notmgivingus enough on offense to make up for his porous defense. Lee can probably hit the same open shots that terry does and better defense. Avery, rondo, and lee could get the bulk of the minutes at guard.
Lot of people didn't realize how rays presence on the floor, both because of his great shooting and because of him running around, helped everyone else. Terry simply does not do either of those for our offense. He only helps if he is scoring.