METAIRIE, La. -- The New Orleans Saints have promoted assistant coaches Ryan Nielsen and Kris Richard into the roles of co-defensive coordinators under new head coach Dennis Allen, the team announced Wednesday.

Nielsen and Richard will continue to oversee the Saints' defensive line and secondary units, respectively.

Allen previously served as New Orleans' defensive coordinator under Sean Payton, while Nielsen was the assistant head coach/defensive line coach and Richard was the secondary coach.

Allen hinted at his introductory news conference that he will likely continue to call plays for the defense, though he hasn't made that official yet.

The use of co-defensive coordinators is much more common in college than in the NFL. However, the Minnesota Vikings used co-defensive coordinators during their final two seasons under coach Mike Zimmer, and the New England Patriots have split duties on defense without naming anyone as their official coordinator over the past four seasons. Other teams have used passing game coordinators and run game coordinators. Richard served as a passing game coordinator for the Dallas Cowboys from 2018 to 2019.

Most likely, Allen wanted to find a way to promote both of his highly valued assistants to make sure to retain them on his staff. Nielsen has been with the Saints since 2017, while Richard arrived in 2021. The Saints ranked fourth in the NFL in points allowed last season and seventh in yards allowed. They have ranked fourth in both categories overall since 2019. And they became the first team to shut out Tom Brady in 15 years with a 9-0 win over the Tampa Bay Buccaneers this past December.

Nielsen and Richard, both 42, were teammates on USC's defense in the late 1990s and early 2000s. Richard went on to play six NFL seasons for the Seattle Seahawks, Miami Dolphins, San Francisco 49ers and Oakland Raiders. Nielsen signed with the Philadelphia Eagles but never cracked a NFL roster.

Richard then became one of the architects of the Seahawks' famed "Legion of Boom" secondary as a defensive backs coach and defensive coordinator from 2010 to 2017. He has had multiple head-coaching interviews in recent years and also interviewed for multiple defensive coordinator positions in the NFL this year.

Nielsen, meanwhile, has had multiple opportunities in recent years to become a college defensive coordinator. But the Saints didn't want to let him go and promoted him to assistant head coach last year while keeping him away from nearby LSU.

The Saints have had the NFL's No. 1 run defense since Nielsen arrived in 2017.

Before joining the Saints' staff, Nielsen spent four years as the defensive line coach and run game coordinator at NC State. His previous coaching stops were at USC, Idaho, Ole Miss, Central Connecticut State, Tennessee-Martin and Northern Illinois.

As previously reported, the Saints are retaining longtime offensive coordinator Pete Carmichael Jr. The team also officially announced former Buffalo Bills and Jacksonville Jaguars head coach Doug Marrone as its offensive line coach and Kodi Burns, who spent last season with the Tennessee Volunteers, as their new receivers coach.

Special teams coordinator Darren Rizzi has added assistant head coach duties to his plate. Rizzi, a 29-year coaching veteran, including a ten-season stint with the Miami Dolphins from 2009-18, joined the Saints in 2019.