Maybe. But then again there are some very clear coaching gaffes in a game. The most obvious offensive blunder were the various play calls in Atlanta where they didn't help their flailing LT. More subtle mistakes were say, the GB Packers playoff game where the Cowboys had momentum and then Micah Hyde picked off the screen pass in the 3rd Quarter.
After the game, Hyde and some others said they knew the play was coming (and it was clear Hyde knew it because you could see him moving over before the snap and then sprinting to the exact spot) because the Cowboys ran the exact same play, with the same formation, in similar situation weeks before in the regular season game.
I think as someone said it best above, a big issue with this team is situational play calling. They tend to get too conservative at times when things don't go their way and then often times, out think themselves thinking they are one step ahead of the other team.
No doubt on Atlanta. Maybe it's semantics, but it wasn't a failure of play-calling, but a failure to adjust the protection scheme.
And the Hyde plan isn't as much a bad play call as GB and Hyde doing what they're supposed to do and study film. Every play the Cowboys run, they've run before.
And regards the situational play calling, again, the perception is based on whether it's successful or not. Had NE not intercepted the slant to the end-zone in the SB, but instead it was completed for a TD, very few would be screaming about the play call. So what if Seattle had run Lynch and he lost 2 yards because NE excelled (as Butler did on the pass), then they had a false start and now it's 2nd and goal at the 8. Then, they pass on 2nd and goal at the 8, but either it's incomplete or a sack. Or they run on 2nd and 8 and pick up 1 yard. Eventually, they fail to score and NE wins.
My point is that the perception of play calling is based totally on the results which are not assured at all prior to the play. Had the SB pass been completed, there would've been people hailing it a good call because it caught NE off guard and "going against the grain."