There seem to be a couple of things going on with the PP.
1) Because of the stupid drop passes, when the puck carrier gets to the line everyone else seems to be mostly standing still. So at that point a dump in (if the carrier is challenged and can't break through) will almost certainly fail because the forecheckers won't get in before the defense gets control. Similarly, if the puck carrier does get in while maintaining control, he is usually forced to the boards where the play is easily pressured because there's no spacing (again because of the lack of movement). This leads to lost puck battles and clears by the defense.
2) When they do manage to get control, there is too much play along the boards. Not nearly enough movement of bodies or puck. This is the one I really don't get, there is so much skill out there in terms of puck handling (at least when they stack PP1, not when they bog it down with Thornton and Simmonds) but they move...in...slow...motion. They let defenders pressure them, then lose the puck battles and the puck is cleared. Is it a lack of confidence after so much failure? Or maybe too much confidence that they can hold the puck and eventually make a great pass?
I think the way to fix it is to put out a consistent 1st until with most of your top offensive players and have them MOVE. Move around the zone like they do when they have those great 5 on 5 shifts where everyone is involved. Become less predictable. And get pucks to the net.