This one seems smart for both teams.
Sign and trade Avery Bradley for JaMychal Green.
Grizz get a defender who can play role similar to Tony Allen but who provides spacing. Celts get an athletic inside-out 4 who can play alongside Horford and also play the 5 in small lineups.
Because let's face it: Bradley is a great team leader and hard worker but he's gone after this season regardless. The Celts aren't paying him and IT, and they're definitely paying IT.
Bradley's minutes at the 2 can go to Smart, Rozier, and Brown. Green picks up minutes left by Olynyk (who will probably get offers too rich to make him worth bringing back), Amir, and Jerebko.
Combine Green with Zizic and you've got a nice infusion of size and athleticism to the Celts' frontcourt. Much needed.