The split in viewpoints expressed here on Green is due to a very distinct split in his performance that is apparent when you look at his positional ... 'splits'.
http://www.82games.com/1011/10BOS12.HTM#byposBasically, Green is a very, very good SF on both ends of the court. Not as good as Paul - but right behind him. And he's a decent offensive PF. But he's simply TOO SMALL to play defense at PF.
The 'net PER' at these two positions (his own PER minus his opponent PER, prorated to 48 minutes) kinda crystalizes the distinction:
SF +6.0
PF -3.2
I am a big fan of Jeff Green but let me be very clear - he SUCKS when expected to play PF except in the situational case where both teams are playing small ball and our team has the speed advantage (which was not always the case when Rondo was all banged up at the end of the year).
Green's misfortune started on his draft day - when he was traded to the Sonics who had just picked Kevin Durant. That doomed him to have to play far too many minutes in his career as an under-sized PF.
In the modern NBA, there are far, far too many PFs that are both tall (6'10" - 7' 0"), AND strong AND athletic. Being just 6' 9" just doesn't cut it there anymore. BBD at least had some weight to help him when being posted up by the taller slow guys. But we all saw him getting torched by the tall fast guys who could shoot over him away from the post. Green is fast, but too small to defend bigger post-up players.
ALL through his career, Green has always looked much better, more comfortable and more productive when playing at SF. But he was never going to displace Durant's hold on that spot in OKC. Durant has averaged 38 minutes per game their whole careers. That has only left 10 minutes at MOST during his time in OKC available for Green to play at his natural position, SF. At OKC, Green was playing ~80% of his minutes at PF!
Here in Boston, he's not going to immediately displace Paul Pierce at SF, either.
But the difference here is that Doc shouldn't be playing Pierce 40 minutes a game anymore.
There is no reason that Doc couldn't get each of Green, Pierce & Allen right around 32 minutes per game by using a rotation that keeps two of them on the floor at all times - with none of them having to play undersized and out of position.
Well, there is a reason - if we don't have adequate bigs. Lack of bigs is what leads Doc to play KG at the 5 or to put Green at the 4.
If Jajuan is the real deal, and we can somehow adequately shore up the C position with one or two more legitimate bigs, then hopefully Doc can avoid that.