My guess is Ainge is waiting until the last moment to see if he can off load his unguaranteed contracts Bogans, Johnson, and Babb for possibly a less desirable contract and a pick. The issue is most teams now have their books in good order with shorter guaranteed deals so he may not find that type of deal. He may just end up cutting Bogans, Babb, and Johnson with his final roster looking like this;
Rondo, Smart, Pressey
Bradley, Thornton, Young
Green, Turner, Wallace
Sully, Bass
KO, Zellar, Fav, Anthony