I think the power play exposes what is really wrong with this team, especially over time while changing out players and coaches: a good power play ultimately requires talent. The Flyers simply don't have high-end talent.
Maybe Konecny, but soberly name a single Flyer that makes PP1 on any of these teams:
Tampa Bay Lightning
Carolina Hurricanes
New York Rangers
Dallas Stars
Edmonton Oilers
Colorado Avalanche
Florida Panthers
Toronto Maple Leafs
Detroit Red Wings
Vancouver Canucks
Look, you can hard work your way against teams October to March. The power play really isn't a big secret in general. I mean, there's a couple vaguely different structures, but it's a half-court game and it comes down to who can play quickly and at a high level. This takes skill. Hard work is great but in a half-court game hard work by players with skill is what it takes. And 5 on 4, if you have to sacrifice either, you keep the talent.
The penalty kill, conversely, takes hard work and some "game smarts." Torts had them working hard and playing smart for the most part. This is reflected by their success (until recently) on the penalty kill.
But regardless of who the coach is, there really is a small bag of tricks in terms of how to play it or strategy. The PP coach simply can't manufacture skill level out of thin air. Apparently, not Rocky Thompson, anyway. I argue no one can.