I know this sounds extremely farfetched and unlikely, but thinking outside the box a bit, could Ainge be taking a page out of Cherrington's book, with the Lester move? Trading him for another asset (DAL draft pick basically), with the plan to try and re-sign him in the offseason with another free agent?
Leaving a Rondo-less Celtics team here to jockey for draft position this year. Maybe with the plan to use this pick towards acquiring a big time player (Kind of like last years failed K Love trade offer)? Also creating more minutes for our young players...
Perhaps he could even turn our rental assets(Wright, Nelson, Crowder) into another pick from a playoff team trying to get over the top, or another young player to use as trade chip?