Guess no further. The Dman the Canadiens need to trade is Ben Chariot. Not because he makes the club worse when he plays, but because the Canadiens might let him walk next offseason. As a matter of fact, Chiarot would be better off on another team.
If the Canadiens' standings worsen, they can wait until the trade deadline. Nobody contests that. However, in this case, time is arguably critical.
In the end, Chiarot is a solid backup defenseman. You can't deny him that after the way he fought in the playoffs. The defence, including him, played well. In his first season with the Habs, he was just mediocre at both ends of the rink, which says a lot.