First time trade idea (and use of the trade machine).
Boston Out: Rozier, Bird (or other salary filler)
Boston In: F. Ntilikina, 2nd round pick
Knicks in: Rozier, Bird (or other salary filler)
Knicks Out: F. Ntilikina, 2nd round pick
Reason for Boston: Ntilikina is 20 and already a good defensive player and a decent passer and but not a scorer. He's also on his rookie contract for 3 more years. He can potentially fill Smart's defensive role if Smart needs to be involved in a future trade for salary reasons. He's kind of a poor man's Smart who can develop on Celtics 2nd unit and let Hayward be the play maker and offensive focus of the second unit.
A second round pick from the Knicks is basically a late first w/out the guaranteed contract.
Reason for the Knicks: They get the better player (hence adding the pick) in Rozier and can let him go next year to clear space for FAs or match if they like him. I think Birds second year is not guaranteed so he can be waived next year for more salary space.
I haven't watched Ntilikina play and I know he's fallen out of favor with the Knicks so I am working off online scouting and talking head analysis, but I wanted to get the thoughts from the board.