FLORHAM PARK, N.J. -- New York Jets coach Aaron Glenn has made the first significant hire for his new coaching staff, agreeing to terms with Steve Wilks to become the defensive coordinator, league sources told ESPN's Jeremy Fowler on Wednesday.

Wilks, 55, was out of the NFL for the 2024 season after serving for one campaign as the San Francisco 49ers' defensive coordinator. He was fired in February 2024, a few days after the Niners' loss to the Kansas City Chiefs in Super Bowl LVIII.

This is a key addition for Glenn, who said Monday at his introductory news conference he wasn't planning to call the defensive plays.

"I want to be the best head coach you can find," said Glenn, the Detroit Lions' defensive coordinator from 2021 to 2024. "In order for me to do that, I think I need to manage the game."

Glenn was attracted to Wilks, in part, because of his previous head-coaching experience. Wilks coached the Arizona Cardinals in 2018 but was fired after going 3-13. He also was the Carolina Panthers' interim coach in 2022. He can be a sounding board for Glenn, a first-time head coach.

Wilks and Glenn have no previous experience working together.

"I'm looking for the best coach," Glenn said Monday. "That's all I'm looking for. He's going to be compatible. And it doesn't have to be from somebody I had; it can be from across the league. When I go through the interview process, everything is on the table and the best coaches will be here."

Wilks inherits a unit that has finished in the top five in yards allowed for three straight years, but there will be significant turnover in personnel. Ten of the Jets' top 17 snap leaders are eligible for free agency, including cornerback D.J. Reed and middle linebacker Jamien Sherwood.

Wilks will replace Jeff Ulbrich, who served as the coordinator from 2021 to 2024 and was the Jets' interim head coach for the final 12 games of the 2024 season.

Wilks, who has extensive experience coaching the secondary, endured some uneven moments with the 49ers.

A unit that led the NFL in multiple categories in 2022 under DeMeco Ryans -- including fewest points per game allowed (16.3) and defensive expected points added (89.58) -- took a step back the following season.

San Francisco still finished third in points allowed (17.5) in 2023, but the 49ers were ninth in defensive EPA (41.48) and sprung significant leaks against the run in the playoffs.

Niners coach Kyle Shanahan explained the decision to fire Wilks by saying, "It just ended up not being the right fit. And it hurt for me to do this, but that's exactly why I had to."

Wilks has 16 seasons of NFL coaching experience, with six different teams. He worked as a defensive coordinator with the Cleveland Browns in 2019.

Glenn is close to filling out other key positions on his staff, including a potential agreement with Chris Banjo to be his special teams coordinator, a source said. Banjo was the assistant special teams coach for the Denver Broncos in 2023 and 2024. 

Lions passing game coordinator Tanner Engstrand is in talks with the Jets for their offensive coordinator position, a source said.

Lions tight ends coach Steve Heiden has agreed to become New York's offensive line coach, according to reports.