You all do know that it's been 8 years since the Barry/Smith thing almost happened, right? And what exactly has Smith done to prove he's any less of a headcase?
Not only is he still a headcase...he's a well paid headcase that will be on the books until the end of 2015/16. He also has a 15% trade kicker.
Even if no picks were included, the Spurs would not trade Green or even just expirings for Smith. No one is touching a player like him on that contract until next seasons deadline at the earliest.