The truth is the Cowboys post Thanksgiving matchups were playing against pass oriented offences that play to the strength of the Cowboys D (secondary) which is why they were able to get some late season wins. As soon as they faced a good running team the the injuries at the linebacker position really showed.
Your not going to win many games giving up close to 300 yards on the ground. I don't care what QB you have back there. Yeah Romo blew it at the end but so did the run defence.