I have the Flyers at 2/3 in the division. While I hate the contract, Hayes is a good player and gives the Flyers at the very least two strong lines, if not 3 with Patrick getting favorable matchups. The offense should be fine, and could be downright scary if the third line puts it together (I think the 4th will be one of the strongest in the league).
Defense will improve if for no other reason than MacDonald is gone, and there is no room for Hagg in the top 6. Braun is whatever and Niskanen is an overall downgrade from Gudas, but the group as a whole will be better balanced.
Washington is the class of the division until they prove they aren't anymore. After that, the Penguins still have Crosby/Malkin, but they're getting older and their supporting cast, especially on defense, has been made worse over the years. Carolina could be quite good again if the goaltending holds up. Islanders are due to fall off, they rode a seriously impressive season of goaltending last year and got unsustainable production from several depth players, even with Trotz, they should not be expected to be anywhere near as good this year. New Jersey and the Rangers got better, but after the top end adds they're still weak in overall talent. Columbus hemorrhaged too much talent this offseason to believe they'll have a successful year.