I don't get the Rozier mania that some people have.
As a starter for his career:
15.3 pts, 6.2 reb, 5.2 ast, 33 mpg, 52.5% TS
Those are better numbers than his career as a reserve, even on a per-minute basis. It's true that he shows out as a starter.
Even so ... as a starter he's basically average. I would say he's below average in terms of creating for others, maybe a bit above average in terms of creating looks for himself.
Even during the playoffs last year he had just a 53.8% TS and averaged .149 WS per 48.
It's not like he's an All-Star or something when he starts.
Kyrie, for reference, has a career 57% TS and is averaging over .200 WS per 48 for the last two seasons.
Personally, I think it would make sense for both the Celtics and for Rozier if they traded him to a team lacking a competent starting point guard in exchange for a more well-rounded backup guard.