I like Asik better than Green, but I don't think I would trade Green straight up for him.
Here's why...
From a teambuilding standpoint, I just don't think it makes much sense. If you trade for Asik, then it is to facilitate a quick turnaround of this franchise. But he is not going to do it himself. If you take away the teams best perimeter scorer in the process, it is one step forward, two steps back. But if you can get Asik without giving up Green, then suddenly it makes more sense, because it should give a quality playoff team, that still has some flexibility.
While I am not thrilled with Green, I think he is one of our more tradable assets, and would be an important piece if we wanted to upgrade the wing position, because of his production and reasonable contract. So, if you are trying to remake the team, I would want to save him for a bigger deal than someone like Asik, who you are buying low on.