FRISCO, Texas -- Dan Quinn is the favorite to become the Dallas Cowboys' next defensive coordinator, according to sources.

Quinn would take over for Mike Nolan, who was fired last week by coach Mike McCarthy, and will inherit a defense that had one of the worst seasons in Cowboys history.

Quinn, who is flying to Dallas for his first interview, according to a source, was fired as head coach of the Atlanta Falcons after five games in 2020, a job he held since 2015. He posted a 43-42 record and took the Falcons to the Super Bowl in his second season.

In going with Quinn, it would be a signal of a return to the scheme the Cowboys employed from 2013-19 under Monte Kiffin, Rod Marinelli and Kris Richard.

Quinn was the Seattle Seahawks' defensive coordinator in 2013-14 before becoming Atlanta's head coach. He employed a 4-3 scheme that mostly used a single-high safety look and helped the Seahawks to consecutive Super Bowl appearances. The Seahawks finished No. 1 in yards and points allowed in his two seasons.

Owner and general manager Jerry Jones was eager to move away from the scheme the Cowboys used in McCarthy's first year because he thought it was too simplistic. Nolan brought a hybrid defense that would use multiple coverages and disguises that would confuse offenses, but it never really happened.

Part of the blame goes to the coronavirus pandemic as Nolan and the defensive staff had to implement their new defense virtually without any benefit of on-field work until a shortened training camp began. The results early were disastrous with the Cowboys allowing at least 34 points in five of the first six games.

Nolan simplified the scheme early in the season but the defense never really took hold. The Cowboys allowed the most points in franchise history (473) and finished with the 31st-ranked run defense.

Part of the blame also goes to not fitting the scheme to the players. Defensive linemen used to attacking upfield to disrupt plays were now asked to hold up blockers. Linebackers did not play downhill and were often late in making their decisions or gobbled up by bigger offensive linemen.

In his two years as Seattle's coordinator, Quinn had a team that was built on defense with the likes of Kam Chancellor, Bobby Wagner, Earl Thomas and Richard Sherman.

He would not inherit that type of talent in Dallas. DeMarcus Lawrence is the highest-paid Cowboy and performed well in 2020, although had just 6.5 sacks. Jaylon Smith led the Cowboys in tackles but there is some question about his future with the team because of potential salary-cap problems. Leighton Vander Esch, a first-round pick in 2018, missed six games with a broken collarbone and high ankle sprain.

Three members of the secondary -- safety Xavier Woods and cornerbacks Chidobe Awuzie and Jourdan Lewis -- are set to become free agents. So is pass rusher Aldon Smith.

The Cowboys feel cornerback Trevon Diggs and defensive tackle Neville Gallimore, their second- and third-round picks in 2020, have high ceilings and second-year safety Donovan Wilson made plays when he moved into the starting lineup.