Hard to gauge when the game doesn't count.
Any QB with Romo's career passing numbers has picked apart their share of defenses, so to say Romo's only special quality is the ability to buy time in the pocket is misleading. He is aging though, and so we can't count on him to carry the offense like he used to.
Romo's biggest flaw is he doesn't know how to throw the ball away and has never had anyone coach it into him. I think Parcells, Palmer, and Lee might have made progress, but it seems like Garrett doesn't even try.