Hayes is injured, before he got hurt last year he was playing at his pre-Flyer level. I wouldn't say he was regressing until we see him play next season. He's a center, which makes him more valuable than Voracek or JVR - because centers are much harder to find than scoring wings - you'd think fans who suffered through Filppula, Lehtera, Patrick, Thompson, Bunnaman, Vorobyev would understand that! Hextall drafted 4 centers with 1st rd picks (Rubstov, Patrick, Frost, JOB) only Frost is playing for them and JOB may end up a wing. The other drafted centers (Vorobyev #104, Laberge #36, Bunnaman #109, Laczynski #169) have contributed zilch, though there's still hope for Laczynski.
Hayes scores at a bottom 2C/ top 3C rate as a Flyer (though he's been injured for about a third of his Flyer games), but when healthy should be better, he's average defensively, solid on the PK (when healthy, struggled last year).
Sure he's overpaid, so is almost everyone who signed a contract the two years before COVID and the flat cap. Those contracts were based on an escalating cap so they're generally a $1-2M overpay. Hayes on a 5x5 wouldn't ire people as much.
If Frost can step up next year, Hayes can play more of a 3C role and we're solid down the middle, but Frost has yet to show he can handle 14-15 ES minutes a night and be a net positive.