The Hextall/Hakstol plan is becoming clearer, they're still a notch below the Caps in terms of talent, but the gap is closing, same with speed v Penguins and Blackhawks.
1) it's all about forward depth, as much as people rag on VdV and PEB, they were better than Umberger, Vinnie, White, Rinaldo, Akeson and some other guys they were running out there the last few years. Now we have guys like Weise, Luby, Leier, Cousins pushing them. Next year we'll have Lindblom, Laughton, AK and maybe Vorobyov in the mix. You can see the difference Luby and Leier make in terms of speed on the forecheck. The Flyers can skate with good teams with all four lines, and while they're a little undersized, they're adding size that can skate.
2) The scheme is being gradually implemented, it must take time for new players to get comfortable, Hakstol had the same problem with slow starts in college, probably because rotating and covering for defensemen has to become second nature for forwards, and defensemen have to make split second decisions without hesitation (pinch, retreat, attack the net). That makes Provorov's growth even more amazing, given the demands of the scheme. I think some of MDZ's struggles are getting back into that flow, he's hitting, shooting but making too many mistakes defending. Once they upgrade the old defensemen, watch out.
You can see how close they are to becoming an elite 8 team, and in a couple years, they may establish themselves as an elite 4 team with the depth of talent coming up. They are now able to play with almost any team on any night. They've kept up with speed teams and gone toe to toe with physical teams, like last night.