Devils fan here who has the Bruins as a #2 (lived in New England and am a fan of other Boston sports teams).
Zacha pure quit on the Devils his last year. He always seemed like a guy who just doesn't really care enough to get through adversity. Has good size, skill, and speed though so he will get his points here and there. But his last year with the Devils was brutal, I know the team was a joke defensively and were effectively out of it by Thanksgiving but there was him floating and there were people who wanted to be part of the solution (Hischier, Bratt, Hughes).
Wasn't surprised to see the trade to Boston light a fire under him since the Bruins have a great culture that can motivate people and his girlfriend was from Boston. But I just doubt he's ever gonna be a playoff warrior. Decent guy to have as depth, but maybe would be worth getting some assets for him that can be flipped for a solid Center or two.
Btw Devils had to move him off center and then had to move him off of PK because the unit was league-worst.