I have two ideas regarding Jeff Green that may allow the Celtics to play some games with the salary cap to the team's advantage.  Green may not be a guy who is going to be a core star player, but at the minimum, if he makes a full recovery, he would be a bench player who would produce enough to be worth more than a minimum salary.

First, the Celtics can waive their 15th man (Daniels?) a few games before the end of the season and sign Green to a pro-rated minimum salary.  If I understand correctly, this would a) throw a few bones Green's way as a good will gesture and b) create a smaller cap hold for Green so that the Celtics would not necessarily have to renounce him if they sign a big free agent such as Dwight Howard.

Second, if the Celtics do renounce Green, then use cap room to sign Green to a small one-year contract, the team would have Bird Rights on Green in the 2013 off-season.  If Green is in a situation where no team is willing to sign him for more than one year, staying in Boston would potentially increase by one the number of teams that can offer him a contract above the MLE if he proves healthy and capable next season.