So uh the problem with that is that's the system they're attempting to run. Same as last year.
I think it's called a Diamond+1 or Triangle+1 PK. 3 guys down low, 2 defencemen at the posts, F1 in the slot. That's supposed to prevent cross-seam passes. The F2 at the top plays a bit higher than F1 and attempts to keep the puck on one-side of the ice by forcing the D to pick a side. Then he slides down to block the seam giving the D with the puck the only option of either going lower down into the zone or passing to his D partner which resets the PK.
Ex:
View attachment 990376
The problem is they've been absolute trash at executing it this year.
What happened after this screengrab is the guy for Dallas in the right corner (Duchene) gets the puck from the D. He button hooks and Brown doesn't respond quickly enough to slide lower, as a result the seam opens up and Rantanen scores.