There are two things that excite me with the mean machine jeff green.
1) his size/speed and rapidly improving defensive prowess.
I hope it improves. Last year with the Celts, for instance, he ranked 298th in isolation defense, in terms of points allowed per possession.
In iso situations, he allowed opponents to score about 30% more points than they scored on Paul Pierce, and to shoot approximately 10 percentage points higher. Similarly, Green was much worse than Ray in such situations.
Perhaps it's a small sample size, but Green's defense wasn't good, and at times (like when isolated) it was terrible.
No idea what the stats showed for his defense in the playoffs (and I am sure you know that I really don't care what they show, because I think defense stats, especially are decieving at best), but I could see a significant change in his defense play in the playoffs compared to when he first got here.
I think he was just starting to feel comfortable enough in the system by that point not to overthink things, and he was very solid overall, and had some spectacular defensive sequences, particularly in isolation against guys like James and Carmelo.
He still has plenty of room to grow on that side of the ball, but I am confident that the more comfortable he gets in a defensive system, and the more regularly he gets to play in his more natural SF position, the stronger he will get on that side of the ball.
Maybe. However, he wasn't a good defender in OKC, and he wasn't a good defender in the regular season in Boston. I don't know how to access Synergy Sports' defensive playoff stats -- I'm sure they're floating around somewhere -- but I don't remember being particularly enamored by Green's playoff D, either. He had some decent moments against Carmelo, but he got burned a lot, too.
I hope he improves. He seems to have the size and athleticism to be a good defender, but I'm not sure he has the right instincts. (I feel the same about his rebounding and passing, which I know you also disagree on.)
By no means do I think he is, or will ever be a lockdown defender. But I absolutely saw improvement. I also think it is tough to guage his defense from OKC, and his first month or two in Boston, since he played so much PF.
I strongly believe that he is not a PF, and should never play that position unless it is to speed up the pace of a particular game, or to match with another team going small.
In OKC he almost always played out of position, and he was forced to do the same thing early in his Boston days, because they had such a shortage up front with all of the injuries.
Although, for the purpose of this argument, its a moot point anyways. I still think he is a MLE or slightly over type player at best, so if they can't get him for the QO (which I think he will sign), then that should be their absolute limit...and even at the MLE, I still might let him walk, since I have not sure he brings the attitude you are looking for in a potential core member of the team going forward.