I don't think you'll find many, if any, who will argue that. He's been a consistently good 5v5 player over his career, and his production rate has stayed fairly constant when given increased ice time. He will certainly help them in the near term, I actually think they're placing in the division, not a wildcard, partially because I see Columbus, Pittsburgh, and the Islanders falling off, and partly because I think they should have a 4-line deep forward corps, which Hayes has a large impact on. Braun and Niskanen, on the other hand, are another story, but since this is the Hayes thread, I'll stick to him.
What many people have a problem with, is that Fletcher has tied himself to Hayes in a way that is very difficult to extract himself from. He's being paid to be a core member of the team, when he arguably might not even be playing center for them in a couple of seasons. Patrick, while disappointing so far, has shown flashes in the NHL of why he was the consensus #1 until his injury. Frost might actually have a higher ceiling than Patrick. If just one of them hits, you now have to pay them what they're worth, AND pay Hayes 7 million a season as he enters his decline, to be your 3C OR 3RW.
I was doing some back of the napkin math yesterday, and the Flyers have roughly $6 million coming off the cap next season. Which means that they will have that $6 million, plus whatever space they have this year, plus whatever the cap goes up, which could very likely be another small number, to sign Myers, Patrick, Lindblom, and a backup goalie. They're looking like they're going to be pushing up against the cap this season, so that leftover cap seems likely to be fairly low, so maybe $11 million all told if they're lucky. You almost have to hope that those guys all have disappointing seasons in order to get them all under contract, because if just one of them breaks out, you're going to have a decision to make. Then the next year, you have Sanheim, Hart, and (maybe) Hagg, again with only about $6 million coming off your cap.
We already know, per Charlie O'Connor, that the Flyers and Sanheim were talking long term, then the Flyers moved to a bridge deal in order to keep the cost down because they found themselves low on cap space. While bridging guys is somewhat effective short term, a lot of quality RFAs are pushing for long-term deals coming out of their ELCs, and the guys you think will be part of your core long term are the guys you SHOULD lock up long term. Where would the Flyers be if Hextall had bridged Ghost or Couturier again on a deal that ended this off-season? Eventually, bridging good players bites you.
Again, I don't think I've seen ANYONE argue that Hayes won't help the Flyers this season - I argued in favor of acquiring him earlier this summer, back when I thought he'd come in at 5x5. He gives the Flyers great depth down the middle. Even if Patrick takes a jump forward and supplants him as the 2C, the cost THIS YEAR is not so big a deal that a 7 million dollar 3C is the end of the world. It's next year, and the year after, as all these prospects start coming off their ELCs and could well be pushing for Hayes' spot on the roster that he becomes an expensive, difficult to move luxury. Not likely to be useless like AMac, but causing issues with his contract all the same. While any of Frost, Patrick, etc. could turn out to be a career-long disappointment, you really need almost all of these guys to miss in order for this contract to not be a hindrance, not 4, 5 years down the line, but in the very near future. THAT'S the concern with Hayes.