I'm not going to overreact to one game. It is definitely not AVs fault. I actually thought Hart played pretty well; he had zero help.
IMO this team should probably be about as good as last year, but has a couple of issues if they want to take the next step:
1. Niskanen was a solid, if unspectacular, #2 and they have not replaced him. They can hope Sanheim or Meyers takes that step but I haven't seen anything, especially defensively, to indicate either of those guys are more than high end 3-4 defensemen. If one of these guys hasn't taken the next step by the deadline at the latest, the Flyers need to make a move for a proven #2.
2. Other than perhaps Hart, they have no elite gamebreakers. That doesn't mean they can't win a Cup, as they might have excellent overall depth if Patrick, Lindblom, etc. pan out. LA did this, though Quick > Hart and Doughty > Provorov.
3. I love what Hextall did, but he made one major miscalculation: he thought he could rebuild without stripping the team down (i.e. trading Simmons, Giroux, and Voracek in their primes). There was no scenario where those guys were still going to be elite players by the time the young guys (Provorov, Hart, Sanheim, etc.) were ready to contribute.