My knee-jerk reaction when I read this at work about an hour ago was that this was a bad idea. With the uncertainty of the health of both O'Neals, trading our starting center didn't exactly seem like a good idea.
However, after about an hour of mulling it over, I'm feel significantly better.
First off, it has become clear that Doc views his most dangerous lineup to be a lineup where a scorer is inserted for Perk. He's consistently closed games with Baby all year. With Green here, I'd expect to see quite a bit of time with him playing with the starters. When you consider that fact that Baby and Green will both likely see time with the starters, we're already covering quite a bit of our "center" minutes already. Thus, even in an imperfect world where Krstic is our only other big, if he can play 20 mpg, I don't see why Green and Baby can't cover all the rest of the backup minutes at the 3, 4, and 5 most nights.
Second, I don't think it will come to that. Quite frankly, if Danny wasn't absolutely certain that he was going to pick up at least one other big on the FA market, there's no way he wouldn've given away Harangody and Erden to for a 2nd round pick.
Finally, if things work out, this team has the potential to be very dangerous as we could rock a playoff rotation primarily focused on our starting 4 + Shaq with a bench of Baby, Green, and West playing most of the backup minutes. Sure, we'll need another center, but Krstic, Jermaine, or a FA pickup should be able to handle most of that. Remember, with Green here, if Doc wants, he can use Baby a lot more at the 5 spot.
I also like where this is going for the future. Jeff Green is a good player. Not good enough to be Rondo's sidekick, but potentially good enough to be a 3 or 4 guy on a title team. Even better, he likely won't get enough PT here over the next year and half to command big money on the free agent market. Thus, we may get him for a reduced rate and then be able to to watch him blow up when Ray and KG depart.