I'd even go further and say the middle six is the issue.
They had something with Koepke-Kastelic-Beecher. Not that they were going to produce they way the started the season all year, but they are 3 of the 4 fastest forwards on the team and were good at keeping the Bruins in the offensive zone with sustained pressure.
The middle six is just a mess. If we say they have a 1st line and a 4th line, can they cobble together two more effective lines out of:
Marchand
Frederic
Jones
Lindholm
Poitras
Letteri
Coyle
Wahlstrom
Brazeau
You could even toss Lysell and Merkulov into the mix.
There doesn't seem to be any permutations that work. If Lindholm is one of the two centers, that means at least 2 of Poitras, Frederic, Coyle have to shift to the wing and I'd argue all 3 are better in the middle.
Marchand is strictly a LW, I'd say the same for Jones. I don't like Brazeau on his off-wing at all, I'm not sure what to say about Wahlstrom or Letteri. Lysell seems to be a RW only, Merkulov plays a lot of C in Providence but up here he's been used on the wing and his off-wing no less.
And to make changes, money has to go out the door, whether that money comes from this group (for example Coyle) or taken from the D (Carlo?).
At least with a rising cap they can probably address it in the off-season. I think they'll be hard pressed to fix this middle six between now and the deadline.