Petts is 22. Dumoulin wasn't even an NHL regular until he was 24. I think Petts can and will improve, and his ceiling is probably around Dumoulin's.
As for cap distribution, it's troublesome that we have so much tied up in guys like JJ, Maatta and Gudbranson--though I have less issue with Gud than the others. If Gudbranson made like a million less, he'd be totally fine. That's sort of nitpicking now. Schultz's struggles are a huge issue as well--we could seriously use some of his transition and offensive ability. The blueline could do with some seriously retooling.
Sort of on the same point; we have nearly $38 million tied up in five guys rapidly approaching "The Decline" (Sid, Geno, Letang, Kessel, Horny), which is one of the reasons I've been saying I hope JR actively and aggressively pursues replacing Kessel this summer. Hornqvist is next on the list, but I think he's going to be a much more effective player than Kessel as age creeps up. Horny does things that don't show up on the stat sheet, and while you need your $5 million dollar guys to show up on the stat sheet, Hornqvist isn't a complete bum when he's not scoring.