Just put Heineman where Armia is. It's criminal on Marty's end he's watching that line and not switching people off of it. Patience with the top line makes sense. This 2nd line had no hope from the start and Dach needs some help to get going, he can't carry Armia right now.
I fear that at this point even a true franchise talent would have difficulty doing so, nevermind Kirby Dach.
But yeah, that's completely, 100% MSL's fault. That line hasn't meshed well at all in every game we've played so far yet he keeps it steady despite NUMEROUS modifications of pairings on D.
Armia is a "slow-and-steady" pure-grind type of player, who works best with other grinders on a fourth-line getting pucks deep, retrieving them, and trying to sustain offensive pressure off of turnovers.
To put him on a second line is to grossly miscast him.
A guy like Heineman, although not ideal himself on a second-line, would bring similar-ish size to Armia while also not clashing as much as Armia does on style of play since Heineman skates WAYYY faster and would better be able to keep up with Dach/Newhook.
I get that MSL is trying to keep Dach/Newhook acclimated to playing with a slower, bigger forward so the transition is more seamless when Laine eventually comes back. But there are limits to that too, and he should not jeopardize his team's success out of personal wishes.