Umm, I don't think the defensive side of the ball is the major problem. The Emperor has not clothes...
http://sportsillustrated.cnn.com/nfl/news/20130108/rob-ryan/?sct=hp_t2_a8&eref=sihpDallas defensive coordinator Rob Ryan was fired Tuesday after his injury-depleted unit struggled in a pair of season-ending losses that kept the Cowboys out of the playoffs for a third straight year.
Ryan was let go a day after running backs coach Skip Peete was fired, and less than a week after Cowboys owner Jerry Jones said things were going to get "uncomfortable" at team headquarters in nearby Irving.
"At this time, the decision has been made to move forward in a different direction philosophically on defense," Cowboys coach Jason Garrett said in a statement. "I have an immense amount of respect for Rob as a person and as a football coach."

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http://sportsillustrated.cnn.com/nfl/news/20130108/rob-ryan/#ixzz2HS9Qe0ok