The trade deadline under the new CBA just isn't going to be that exciting. There are fewer bad contracts, and fewer teams willing to go for broke by acquiring big contracts. The luxury tax penalties are too great.
Hand in hand with that is the following bit of new wisdom:
Don't sign players to deals worth more than the MLE unless you expect to keep them until the end of their deal.
If you don't view Brandon Bass, Jeff Green, or (this summer) Avery Bradley as a long term piece, don't sign them.
Unless you include them in a deal with a major piece like Rondo, you're not going to be able to trade them. Not even in a salary dump for a 2nd round pick.
1st round picks are held more tightly than ever by teams, and the guys that get moved are on very small contracts, mid-sized expiring deals, and, occasionally (but usually during the summer) major pieces.
Having cap flexibility means shrugging off your bad contracts by giving up significant assets, or actually having discipline in the first place to not hand out deals to players who aren't going to put you over the top.