You'll find if you evaluate the class beyond the top 4, Desnoyers is as good as any other prospect or center in the class.
There isn't a potential 1C outside of Misa and Hagens. Desnoyers and Frondell are the next two and they are both very similar.
Like you I'd have Desnoyers roughly on the same level as Frondell. More precisely, they'd be 7th and 8th on my list right now if Ryabkin hadn't crapped the bed to start the year and if McQueen also hadn't re-aggravated an herniated disk in his back early in the season.
But since we live in a world in which McQueen's health is uncertain and Ryabkin has experienced an "Aatu Raty type" of downward turn as a prospect, I currently would have Frondell 5th on my list, and Desnoyers 6th.
As for there having no potential #1 centers available in this year's draft after Misa and Hagens, I respectfully disagree.
Though they may not be nearly as "shoe-in" as Misa and Hagens (not even in the same stratosphere), I believe that both Frondell and Desnoyers (McQueen and O'Brien too) have #1 center upside if they reach their absolute top potential.
The problem is that both Frondell and Desnoyers will be picked very high at the draft, thus requiring significant draft pick investment, that McQueen's health scares me (would require lots of validations by team doctors to approve a top-10 draft pick selection for me), and that O'Brien's floor is VERY low considering how raw he looks at times defensively as a centerman.
So yeah, Misa/Hagens would be amazing, Frondell/Desnoyers too, but McQueen and O'Brien would need a lot of faith/scouting.
In the NHL I'd argue that our biggest hole is at 2C, but in our prospect pool we already have several guys that could potentially fill that role with positive development (Hage, Beck, Kapanen).
So I'd say that our true highest current need in our prospect pool would be RD considering that Mailloux has kind of stalled this season and that Reinbacher might have trouble recovering from that devastating knee injury he suffered in preseason.
Just, a thing that I find really unfortunate for us is that my three top-ranked defenders so far in this year's draft (Schaefer, Smith, and Aitcheson) are all left-handed defensemen.
And the options on RD get thin pretty quickly once the likes of Hensler and Fiddler (Mrtka too but I don't like his game that much) are off the board so that might not work out very well on that front for us.
Unrelated, but a guy that I think is underrated that we could potentially manage to nab late-first would be someone like Nesbitt.
He has "+" size, shows some nice skills for a big guy, plays a good, principled type of game as a center, and though I don't love his skating it also isn't anywhere near as bad as guys like Bill Zonnon or Nathan Behm.
Nesbitt could be worth a shot if we decide to go for something else than a center with our first pick.