IMO, the biggest difference from the start of the year is that they've gotten too stuck in their PP roles.
At the start of the year, either because they were rolling or because they didn't have their system/strategy locked in, they moved around a LOT more. They got to get back to that.
If he has possession, theres no reason Rielly cant take the puck in down low, Matthews cant move to the high slot, and Marner can't be on the point or in the crease.
When the pens were rolling in Crosby's prime, Malkin and him never seemed to be staying still and it works. We're stuck with Matthews set up in his shop and nobody to get him the puck while Marner doing the same blueline curl to try and pull a defender away from a passing lane and it isn't working right now.
Net front presence should be the only person that might remain there the whole shift, but even that isn't 100% true.
More movement (players and puck passing) are needed. We are already trying to crash the net and have a net front presence, but the first step is player movemenr so the extra guy can sneak into a good scoring position and the passing lanes can open.