Updated

The Dallas Cowboys fired defensive coordinator Rob Ryan on Tuesday.

Ryan was let go after the Cowboys missed the postseason for a third consecutive year. His firing ends a two-year tenure with the team.

"I want to express my appreciation to Rob for all of his efforts and contributions to the Cowboys over the past two years," Cowboys head coach Jason Garrett said in a statement. "At this time, the decision has been made to move forward in a different direction philosophically on defense. I have an immense amount of respect for Rob as a person and as a football coach and I wish him and his family the very best."

Under Ryan's tutelage, the Cowboys ranked among the league's top 20 total defenses, placing 14th in 2011 but slipping to 19th in 2012, perhaps in large part as a result of injuries to many of Dallas' key defensive players.

Ryan becomes the second casualty of the Cowboys' coaching staff. Running backs coach Skip Peete was fired on Monday.