This doesn't tell the whole story. The Cowboys are 27th in the NFL in total 3rd down attempts, and are 18th in three and out percentage. On third downs, 92 of their 116 attempts are 6 yards or more, or 79% of the plays. This tells me that the lack of a running game and a failure on 1st and 2nd downs hampers their third down efficiency. The stats also show that Romo plays very well on first down. Romo has certainly not played well since the Denver game, but those numbers above have some context to them.