1- Green isn't that great.
2- the Celtics would never trade for Bargs. That is one way ticket for Ainges early retirement. "Hey I know I traded away are defensive anchor but I've got a really great solution...."
3- Green is a tweener who prefers the 4 over the 3. We just have to many guys at the 4 all of the same caliber, and Green IMO would be just one more.