I don't think Green will be as good as Bias would've; however, it is true, Green could really make them more effective.
Also, as others have said, while we can talk all we want about sabermetrics and how he played at the 3 and 4 while in OKC, the fact of the matter is that he won't be playing the 3 or the 4 in OKC anymore, he'll be doing it in Boston. And as we've seen with guys like Shaq, when you play with a bunch of All Stars and Future Hall of Famers, you get a lot more open looks and can look a lot better.
I wouldn't sell him short yet.
I also wouldn't say that he's going to work out yet.
Time will tell.