I'm really speaking to the offense. The defense doesn't have enough quality personnel to matter. Often they are playing technically sound but just can't get it done due to their own limitations.
On the offensive side though, I 100% think that it is on the coaching. A hold here and there has not been our problem. We don't miss many FGs. Romo throwing INTs to DBs because the WR didn't run the right route, not finding the hot read on an OBVIOUS blitz, too many line adjustments, missed assignments, etc. is coaching. The offense just does not have a culture of execution. It wants to run hundreds of plays/routes and adjust on the fly to what the defense presents. THat requires a TON of recognition by the QB, WRs, OL, it requires tons of chemistry, and you have to be right. At some point, you have to simplify it and allow the players to just execute on something they have practiced over and over and over.