For whatever reason, the Cowboys were not ready to play. Which of course is inexcusable. You have a home game, and if you win, most likely the divisional game is to be played at home too.
But nooo! They came out flat as a pancake. What's even more perplexing is the geniuses that call the schemes decided that they would switch up from what they've been doing all season. So, Dan Quinn the DC decided to change to zone coverages which the team normally does not use. On offense, McCarthy went away from primarily throwing on first down to relying on a running game that had pretty much been nonexistent all season. It's akin to changing horses midstream.
In addition to all of that, they made sickening history by being the first second seeded team in NFL history to lose to a seventh seed. So, all in all, yes, they had a successful season. Yes, they won the NFC East. But Cowboys fans EXPECT MORE! Much more!