We have to remind ourselves that this team, on paper, never should have been 14-2 and probably wasn't actually as good as that record suggested. Going into this year, nobody should have expected a Super Bowl run. It was remarkable that they earned a first round bye, let alone the best overall record in the NFL.
Unfortunately, as the Cavs can attest, having the best overall regular season record doesn't mean much beyond getting to play your games at home.
The Patriots are a very young team with a questionable defense that was overly reliant on forcing turnovers all season long. They had a great offense that was rebuilt on the fly, but that's not good enough in the playoffs when other teams play with extra fire and determination on defense.
Unfortunately, right now the Pats are the anti-Celtics. They will turn it up during the regular season via an MVP-caliber quarterback and a top-notch offense, but they don't have the experience or mental preparation to handle the extra physicality and importance of the post-season.
Compare that to the Celtics, who get mired in the regular season but have the experience to stay focused in the spotlight and the true grit to play with an edge on both ends of the court in the playoffs.
Maybe by next season or the season after that, the Patriots will have bolstered their offensive line and added an actual pass rush, and they will have gotten enough experience and developed enough hunger to succeed in the post-season. We will see. It also takes a lot of luck...by the time the Pats have the experience and the personnel, they might have to deal with a lot of unlucky injuries (see: 2008 Patriots).
I'm expecting a 10-11 win season next year, a playoff win in the wild-card round, and then a loss in the divisional round. If the Patriots reach or exceed that, I'll be happy. I'll try to manage my expectations better next season so I don't get so disappointed when these young, inexperienced, and honestly rather soft Patriots drop another big game.