It's not that hard to figure out, you just won't like the answer.
Like many on this board you WANT it to be a Dak problem when it is really not.
The OL was well below average, the WR corps was well below average, and you lost the explosive RB before half-time.
You also happened to be playing the league's top ranked defense.
All that was probably fine if you had luck with health on defense but you lost CB2 and CB3.
It left you very susceptible to short passing and run game teams.
And you had a kicker who couldn't even make a 25-yard kick.
Getting to the divisional round was EXPECTED level of performance not a major disappointment except to goofy fans with their heads buried in the sand.
People KNEW BEFORE the year this team was a bit undermanned.
The biggest disappointments were the Kicker falling apart when it mattered most, the zero return for Tolbert and Washington as expected WR3/4 and the lack of run stop until they signed Hankins.