I don't understand the fixation with the criticism of a "player who does not play defense." Ray Allen was not known to be a defensive player. So was PP, Nate, or any other current Celtic player (except for maybe a few). Yet, most of them has thrived in the Celtic's system. If Davis cannot be re-signed, there are other players in next year's free agent pool that can come in and play. I am sure the C's will sign him or at least, attempt to re-sign him long term. If not, a sign and trade should be able to get a decent player in return.
3 Players who are free agents next year that can be good investments:
Tyson Chandler, J.R. Smith and Roger Mason. Tyson and Smith are under 30 while Mason is only 30 y/o. I'm sure I will get plenty of criticism with that opinion.