Regarding the Devils - Anything can happen and you never know what can take place if you just make the playoffs (look at Florida last year), but I agree with you - the season ended with us having a record that is pretty indicative of how the team performed and what they were capable of.
Bad defense, bad coaching, bad goaltending, injuries, young rookies getting more playing time than they should, poor PP, poor home record, etc. there's reasons for each of those things, but when you have all those collectively, generally you're not going to make the playoffs.
Regarding other teams, I'm ecstatic and think it's absolutely hilarious that the Flyers were over achieving much of the year and looked like they were going to make the playoffs, and absolutely crashed and burned the final 15 games of the season. I know they weren't expected to do much at the beginning of the year, but their collapse can't go unnoticed by the GM and owners.