FRISCO, Texas (CBSDFW.COM/AP) – After a season of having one of the worst-ranked defenses in the NFL, the Dallas Cowboys have decided to part ways with defensive coordinator Mike Nolan.

Coach Mike McCarthy hired Nolan from New Orleans, where he was coaching linebackers, when McCarthy replaced Jason Garrett a year ago. They worked together for a season in San Francisco in 2005, when Nolan was coach and McCarthy was his offensive coordinator and the 49ers finished 4-12.

Dallas also fired defensive line coach Jim Tomsula, another former San Francisco coach.

“I am appreciative of my relationships with both Mike and Jim, and I am grateful for the contributions that both of them made to our team under difficult circumstances in 2020,” McCarthy said. “These are never easy decisions to make, and we wish them, and their families, the very best in the future.

The Cowboys tried to implement a new scheme despite having no in-person time with players during the offseason because of the coronavirus pandemic. The start of the season reflected the limited training, with Dallas allowing at least 34 points in five consecutive games following a 20-17 loss to the Los Angeles Rams in the opener.

Dallas won twice despite the failures of the defense during that five-game stretch, beating Atlanta 40-39 and the New York Giants 37-34. Both games ended with field goals on the final play.

The Cowboys, who finished 6-10, gave up 473 points (29.6 per game), topping the previous club worst of 436 from 2020. The per-game average fell a little more than point shy of the franchise record of 30.8 from the inaugural season of 1960, when Dallas finished 0-11-1.

Dallas bottomed out at 3-9 with a 34-17 loss to Baltimore that almost became the second 300-yard rushing game against the Cowboys this season. The Cowboys gave up a franchise-record 307 yards on the ground in a 49-38 loss to Cleveland in Week 4.

Improved play by the defense during a three-game winning streak that kept Dallas in the NFC East race until the final weekend wasn’t enough to save Nolan.

While owner Jerry Jones maintained all season that McCarthy would return despite a tough debut in Dallas, the quick departure of McCarthy’s most important hire will be a mark against the former Green Bay coach.

After taking the job, McCarthy decided to keep the play-caller already in place in offensive coordinator Kellen Moore, who signed a contract extension just before the finale when he was in the running to take over at his alma mater, Boise State.

Nolan was a defensive coordinator for the first time since 2012-14 in Atlanta, a stint that ended with the Falcons last in the NFL in total defense and passing defense and close to the bottom in points allowed. In 2013, Atlanta was second-to-last in rushing defense.

Tomsula had spent the previous three years as Washington’s defensive line coach after a year out of the NFL following his firing as coach of the 49ers. He spent eight seasons as San Francisco’s defensive line coach.

(© Copyright 2021 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)

CBSDFW.com Staff