They don't have a lot of cap room to work with, but can certainly make something work. One of the things they can do involves a trade that includes a young player who hasn't quite proven themselves yet.
Kakko Kaapo just hasn't worked out in New York. Being bounced around the lineup and not being used much in the playoffs, there just isn't a space for him anymore on the roster. It'll be tough departing with a former #2 pick, but it has to be done.
Boston has to fill in that void, and why not get younger and give someone who needs it a fresh start? Or, they can trade Debrusk's rights for Kaapo's rights. A one for one deal, or maybe NY throws in a pick.