I'm going to boot him because he has value and is not doing enough. Where does he play in your makeup of the team? The Devils in the playoffs had Bratt, Meier, Noesen, and Bastian playing RW in the playoffs, and then they have Gritsyuk who plays RW in Russia. They can move Meier to LW again if they want to make room for Mercer, but if Hughes-Bratt are a locked in duo, that locks out Mercer from that line - now he either plays on a 3rd line or with Hischier.
He's the best piece in order to get a 3C. He is not one himself.