Why do hawks do this?

Hawks get the 3-point shooter that they desperately need to space the floor. They are sad to part ways with both Collins and Griffin but this move would help the Hawks a lot.

(Basically, they trade a starter who can't shoot and a bench player who can shoot for a starter who can and a bench that can't.)

Why do Knicks do this?

Knicks get a promising young forward who can be a vital piece to their young core.

Barret - Griffin - Toppin