The "he" is Heinen, right? We're never going to agree about him, I accept that. But I want to offer a defense against "he's terrible in the playoffs".
Ok, just 1 point in 8 games, +0. That's clearly not great production. But dig a bit deeper. He ranked 1st amongst the Bruins for on-ice SF% 5v5, 3rd in CF% (shot attempts) and 6th in high danger chances for. That suggests some solid play. And per the eye test I thought it was much of the usual from Heinen - battled hard, responsible both with the puck and on defense, made a few really smart passes, can't recall him being involved in any major defensive gaffes or goals against.
He was also injured to the point that he missed 5 games and was probably hampered for one or two before that. But I don't want to rest on that as an excuse. Would you like to see more? Of course, but for a utility who can soak up some decent minutes, keep the opposition honest, and can be used in a variety of situations, I was content with his play.
Depends what he wants, but if he's willing to talk fair money I'd like to see him re-signed. I'd agree he's not really a 4th liner. But I don't think there's as many guys ahead of him in the top 9 as you suggest. Depends how they want to construct the roster and who they bring in. At the least, he has to be in the conversation for being worth keeping around. We'll see how it shakes out.