A disappointing season spent mostly without quarterback Cam Newton on the field cost Ron Rivera his job as coach of the Carolina Panthers.

The Panthers fired Rivera on Tuesday, parting ways with him with four games left in the regular season. Rivera became the second NFL head coach fired this season, following the Washington Redskins’ Jay Gruden.

“I believe this is the best decision for the long-term success of our team,” Panthers owner David Tepper said in a written statement released by the team. “I have a great deal of respect for Ron and the contributions he has made to this franchise and to this community. I wish him the best. I will immediately begin the search for the next head coach of the Carolina Panthers.”

The Panthers, who are 5-7 following Sunday’s loss at home to the Redskins, elevated secondary coach Perry Fewell to interim head coach.

Rivera, 57, is a respected coach who is likely to be a candidate for other head coaching vacancies around the NFL this coming offseason. He took the Panthers to the playoffs four times in his first seven seasons after being hired in 2011. The Panthers went 15-1 and reached the Super Bowl during a 2015 season in which Newton was named the league’s MVP.

But Carolina lost that Super Bowl to the Denver Broncos, and success has been more elusive since then. The Panthers returned to the playoffs after the 2017 season but lost in the opening round. They missed the playoffs last season, when a 6-2 start gave way to a 1-7 finish, and they are struggling again this season with Newton sidelined by a foot injury that has made his future with the franchise uncertain.

Kyle Allen has had some good moments filling in for Newton at quarterback, and tailback Christian McCaffrey has become one of the league’s most dynamic players. But the Panthers rank only 21st in the NFL in total offense and 22nd in total defense, and they’ve lost five of six games since a 4-2 beginning to fall out of realistic postseason contention.

Sunday’s 29-21 defeat to the Redskins left the Panthers with a four-game losing streak and prompted action from Tepper, the hedge fund billionaire who purchased the team last year from Jerry Richardson amid an NFL investigation into allegations of workplace misconduct involving the franchise’s original owner.

Tepper said the Panthers will hire an assistant general manager and a vice president of football operations to bolster their front office decision-making staff.

“We are going to take a comprehensive and thorough review of our football operation to make sure we are structured for long-term sustained success,” Tepper said. “Our vision is to find the right mix of old-school discipline and toughness with modern and innovative processes. We will consider a wide range of football executives to complement our current football staff. … We all must recognize that this is the first step in a process, but we are committed to building and maintaining a championship culture for our team and our fans.”

Read more on the NFL: