I like Green's energy. I really think some people are underestimating the effect a training camp and playing with Rondo (not to mention the rest of this team) is going to have on him.
Even if he doesn't get dramatically better than he was in Oklahoma City, I think that those factors can actually make him a much better player here than he was there.
Just look what happened to what appeared to be a washed-up Shaq when he had Rondo throwing him alley-oops and lots of talented scorers drawing defensive attention away from him.