OK, this is out of left field:
Trade Gordon Hayward to Utah for Derrick Favors (in last year at $17 mm) and Ricky Rubio (UFA, so sign (at about $12 to match with Hayward) and trade would be required).
Boston gets a solid guy up front, in prime of his career (27) to play with Horford, brings in Rubio as either starting or, more likely, backup, PG, and reduces its wing clutter.
No more complaining by Silky that you can't start Hayward, Brown and Tatum together (actually, I'm starting to concede his point)!
Utah more than anyone including Boston would appreciate the value of Hayward, as a solid second scorer next to Mitchell.
I realize this may be perceived as a poor return for Gordon, assuming he would return to his old Jazz self, but nobody knows if he will. Plus by getting rid of Hayward's contract, and Favors becoming an UFA after next season, you develop more roster flexibility.
Did not run through trade machine, and know there are some wacky rules regarding sign-and-trades, but thought I'd put this out there, so have at it!