I think that the Cowboys should have fired Bob Ryan. He was hired to do a certain job, and that was help the team win. When someone is not doing their job, then it is a possibility that they will get fired. Now they can have someone else in his place that will help them to win.
I like Rob Ryan but the firing was justified. The Cowboy's defense just wasn't getting it done. They were getting shredded all year. I admit that they had some key injuries but that is no excuse. Robert Griffin is a rookie quarterback and he was owning them a few weeks ago.
While the Cowboys did not get into the playoffs, this was not a fault of the defense. When the offense turns it over three to four times a game, it is difficult for a defense to put up consistent stops and stop opponents from scoring. He definitely helped the defense improve in most if not all of the main metrics of defensive statistics, so he should not have been fired.
As much of a fan as I am of any decision that makes Rex or Rob unhappy, he wasn't the problem with the Cowboys. The Cowboys have a quarterback that can't handle the big stage and an owner that doesn't know how to be an owner. Tony Romo's bad decisions and Jerry Jones putting his hands on every decision the organization makes are why it fails. Romo may go soon, Jones is going to drag this thing down with him Al Davis style.