After nine seasons with the Dallas Cowboys, defensive lineman Tyrone Crawford has opted to retire, coach Mike McCarthy said Thursday.

Crawford, 31, battled numerous injuries the past few seasons, including double hip surgery that limited him to just four games in 2019. That played a part in this decision, as he was set to be an unrestricted free agent but decided his body could not withstand the rigors of the NFL.

The Cowboys selected Crawford in the third round of the 2012 draft. After playing a reserve role as a rookie, he tore his Achilles in training camp in his second season. He returned as a full-time starter in 2014 and had 37 tackles, 3 sacks, 4 tackles for loss and 29 pressures.

In 2015, the Cowboys signed him to a five-year extension worth $45 million, and he posted 19 sacks from 2015-18, including a career-high 5.5 in 2018. His ability to play multiple spots along the defensive line ultimately hurt some of his production because the coaches would not settle on him playing defensive end or tackle.

Crawford battled through shoulder injuries that would require surgery, but he became one of the defensive leaders, which was missed during his absence in 2019.

He started three of 16 games in 2020 and finished with 17 tackles, 2 sacks and 13 quarterback pressures.

If linebacker Sean Lee, who is a free agent, does not return for a 12th season, then DeMarcus Lawrence, a second-round pick in 2014, would be the Cowboys' longest-tenured defensive player. Randy Gregory, a second-round pick in 2015, would be the second-longest.

Dallas has signed defensive end Tarell Basham as well as defensive tackles Carlos Watkins and Brent Urban this offseason.

"You can't have enough 6-5, 260-, 265-pound athletes on your team," McCarthy said.

With the firing of coordinator Mike Nolan and the hiring of Dan Quinn as his replacement, the Cowboys' defense will have a new boss, but not necessarily a new look as McCarthy said they'll run a similar scheme as last year.

The defense ranked 31st vs. the run, 23rd in yards allowed per game and 28th in points allowed last season. It was tied for seventh with 23 takeaways.

"When you look at our team from 2020 to 2021, the largest change is clearly on defense," McCarthy said. "That's something we felt was needed. ... [But] this isn't a start-over situation. We're able to build on some of the things we were able to accomplish last year."

ESPN's John Keim contributed to this report.