You want a player who wants to play and wants the ball. Most NBA coaches, not all, are pretty up front about what to expect in your role. He only played 6 minutes on Tues but had a +3, 2 assts, 0 TO's, and 0-1 from field. Again very solid for a guy auditioning for playing time elsewhere or in future. According to Boston press, the most likely guys from summer roster to make big club are R.Williams (already under contract), rookie F Grant Williams, rookie G T Waters, M Strous, and possibly G Edwards and/or even Taco Fall. Not sure about rookie from Indiana currently rehabbing thumb injury. I believe they can have 16 players on roster and 13 max can dress for game. It may help Elmore get a look at the G league but he may also be better off playing over seas. Really his best situation will be any situation where he gets lots of PT vs best competition he can.
Celtics are 3-0 so will almost certainly make 8 team single elimination playoffs, so they have at least 2 more games.