The San Francisco 49ers have fired defensive coordinator Steve Wilks three days after they lost Super Bowl LVIII to the Kansas City Chiefs and a little over a year after he was hired.

"It just ended up being not the right fit," said 49ers head coach Kyle Shanahan during a Wednesday news conference.

"We felt pretty strongly that this was the decision that was best for our organization,” Shanahan added. “Even though it was one I didn’t want to make, it was something that once I realized that a different direction was what’s best for our organization, it’s something that I have to do.”

The move comes after Shanahan said Tuesday he expected all of his coaches to return for the 2024 season. He also praised Wilks' work with the defense this past season, which had up and down results.

"I thought they’re one of the reasons that we got this far," Shanahan said Monday. "I thought they did a number of good things. They did a lot of good things in that game [Super Bowl LVIII], too. Just like our whole team. Our team did a bunch of good things this year but came up short in the last game."

How the Super Bowl ended on Sunday night has brought scrutiny on Wilks and how the 49ers' defense played. Defensive end Nick Bosa said the unit "could’ve been more prepared" for zone-read plays that Patrick Mahomes successfully executed on short-yardage situations late in the game.

"You kind of have to anticipate Mahomes wanting to have the ball in his hands," Bosa said. "We played plenty of read-option teams, so we have the answers for it. But it’s tough when you play a team like that that can beat you in all kinds of different ways. It ended up being very big few moments where they did pull it out. We’ll learn from it."

Shanahan himself said a timeout he was forced to use with 2:48 left in overtime was due to a defensive call he didn't like from Wilks.

"Yeah, I didn’t like the look [the defense was] in and some of our players looked a little gassed," said Shanahan, who previously moved Wilks from the booth to the field during a three-game losing streak in October.

The 49ers hired Wilks on Feb. 9, 2023 to oversee the defense after he spent the 2022 season as the Carolina Panthers' defensive assistant and later interim head coach following Matt Rhule's dismissal.