Been saying since last season, Rozier is a streaky offensive player and a poor ball distributor. When he's hot, he's a tremendous weapon on offense--but he doesn't seem to get hot coming off the bench, and he's obviously not going to start when Kyrie is healthy.
Ainge made the right decision going with Smart for the long term. Smart, for all his warts, is a more impactful player and more valuable teammate. His defensive hustle makes an immediate impact when he enters the game, and he's become a fairly skilled passer--the ball movement when he's distributing is certainly MUCH better than when Rozier is out there pounding the rock.
I appreciate what T-Ro did in the playoffs, but when he's not cooking on offense he isn't much help. If he's that disgruntled I think you have to trade him and let Smart/Brown absorb his minutes.
(Kind of funny that we were all worried about Marcus Morris, but he's been absolutely balling in limited minutes while T-Ro is the disgruntled odd man out.)