The Seattle Seahawks have fired defensive coordinator Ken Norton Jr. and defensive passing game coordinator Andre Curtis, a significant shake-up to Pete Carroll's coaching staff on the heels of the team's worst season in more than a decade.

The Seahawks announced the moves Tuesday.

Seattle has already begun its search for a new defensive coordinator, requesting permission to speak with Denver Broncos defensive coordinator Ed Donatell, a source told ESPN's Jeremy Fowler. Donatell, 64, has coordinated and coached NFL secondaries for decades -- a Seattle soft spot in recent years -- and has history with Carroll at multiple spots.

The 55-year-old Norton, a longtime Carroll assistant, was the Seahawks defensive coordinator for the past four seasons. The 2021 season typified the mixed-bag nature of his tenure, with the Seahawks finishing fifth worst in yards allowed (379.1 per game) and tied for 11th best in points allowed (21.53).

For the second straight season, Seattle's defense was gashed at a historic rate early on before rebounding with a strong finish. Carroll mentioned that trend last week while citing several things that went wrong for the Seahawks during a 7-10 season in which they suffered their most losses since 2009, the year before he and general manager John Schneider arrived.

"Defensively, we didn't start fast enough in this season again," Carroll told 710 ESPN Seattle a day after the season finale. "That's two times in a row we didn't start fast enough, and we found ourselves and put up some good numbers that indicate how you're playing. Just all of that just didn't happen soon enough."

The 2021 team allowed at least 450 yards in four straight games (Weeks 2 through 5), a franchise record and tied for the longest streak in NFL history. The defense got on track after a shake-up at cornerback in which Tre Flowers was benched (he was later released) and D.J. Reed moved back to the right side.

The 2020 team allowed the most passing yards through nine games in league history and topped the previous mark in only eight games. It allowed the fewest points in the NFL over the final seven weeks of that season.

In his end-of-season news conference Jan. 10, Carroll declined to say whether Norton and first-year offensive coordinator Shane Waldron would return.

"I'm not addressing any of that stuff," he said. "This is that day when a lot happens in the league to coaches. It's a day that we respect differently than others. Until you're in it, you can't really relate to all of the impact of this day. But our coaches worked their tails off. They did a great job. We started our season-ending meetings today, and I'll get with all of these guys before we get out of here. I'm really proud of the work everybody has done, and I feel fortunate that we are doing this thing together."

Curtis joined Carroll's staff in 2015 as an assistant secondary coach in charge of safeties. He was elevated to defensive passing game coordinator in 2018.

Norton, a former Pro Bowl linebacker, played for Carroll in 1994 and 1995 when Carroll was the 49ers defensive coordinator. Norton coached under Carroll for 15 of the previous 18 seasons dating to their time together at USC.

One question now is whether Carroll will again hire one of his past assistants to run his defense or go outside of his own coaching tree. Dan Quinn, Kris Richard and Norton had all previously worked under Carroll or were already doing so when they became Seattle's defensive coordinators. Gus Bradley, a holdover from Jim L. Mora's 2009 staff, was the lone exception among the four defensive coordinators Carroll has had in Seattle.

Clint Hurtt, Seattle's defensive line coach and assistant head coach, is the highest-ranking defensive assistant on Carroll's staff.

Carroll brought Norton with him to Seattle from USC in 2010 as the Seahawks linebackers coach, the same role he held for the previous six seasons with the Trojans. The Raiders hired Norton as their defensive coordinator in 2015 and fired him midway through the 2017 season. Carroll brought him back to Seattle in 2018 as defensive coordinator after parting with Richard.

That change coincided with the transitioning away from the famed Legion of Boom secondary. Kam Chancellor suffered a career-ending neck injury in 2017 and Richard Sherman was released after that season. Earl Thomas held out during the 2018 offseason and returned only to suffer a broken leg in the fourth game. He then left in free agency.

In four seasons under Norton, the Seahawks ranked 11th, 22nd, 15th and tied for 11th in points allowed. They were 16th, 26th, 22nd and 28th in yards allowed.

The 2021 Seahawks finished 25th in takeaways and tied for 22nd in sacks despite the expectation that their loaded pass rush would be among their biggest strengths. Strong safety Jamal Adams, who set the NFL sack record for a defensive back with 9.5 in 2020, didn't record a sack this past season while blitzing less often. He landed on injured reserve because of a shoulder injury he suffered in Week 13.

Norton made three Pro Bowls and was once named a first-team All-Pro during his 13-year NFL playing career. He holds the distinction of being the only player in NFL history to play for three straight Super Bowl winners: the Dallas Cowboys in 1992 and '93 and the 49ers in '94.

The son of former heavyweight champion Ken Norton Sr., Norton Jr. has said that living through the ups and downs of his father's boxing career as a kid helped prepare him to handle the scrutiny he has faced when Seattle's defense has struggled.