Mike McCarthy’s debut season with the Dallas Cowboys was bitterly disappointing. Of course the multiple injuries, particularly to offensive starters, was major, but second to that was the frequently putrid performance of the defense. It led to the decision to not keep Mike Nolan. He may have been a bit of a scapegoat, but there is little disagreement about him failing in multiple ways. Now Dan Quinn has been brought in as the new defensive coordinator. His success or failure will not only be a big factor in the success of the team this year, it will be the primary determinant of how long McCarthy hangs onto his own job.