The Panthers invested heavily in their offensive line last year, signing left tackle Matt Kalil and re-signing guard Trai Turner to a four-year extension. That could leave little room for Norwell, who did not allow a sack in 2017, according to Pro Football Focus. (Ryan Kang/AP Images)

A product of Buena Vista High School in the heart of the Colorado Rockies, Solder could be set for the biggest payday of any offensive lineman on the market, given his experience and his background at a premium position (left tackle). A biceps injury cost him 12 games in 2015, but he has played at least 15 games in every other season of his career, and he played all 16 games in 2014, the year in which he battled testicular cancer. (Winslow Townson/AP Images)

Pugh's 2017 season ended seven games early because of a back problem that forced him to injured reserve, but it did not require surgery. Pugh can play left guard and right tackle, but over his first five seasons, left guard has proven to be his most effective spot. (Aaron M. Sprecher/AP Images)

After moving from guard back to his college position of center in 2015, he began emerging as one of the league's best young centers before being derailed by injuries, including a concussion that forced him to injured reserve last Nov. 4. Richburg's long-term trends still show promise; his penalty rates have steadily dropped over the course of his career, and he is a strong, quick and young center. (G. Newman Lowrance/AP Images)

Whoever signs Mewhort will be taking a roll of the dice on his knee issues. The five-year veteran was placed on injured reserve after five games last season and has missed 17 games in the past two campaigns, sidetracking what had been a promising start to his career. (Peter Read Miller/AP Images)

Berger is still effective, starting all 16 games for the Vikings last year. He turns 37 in May, but the 6-foot-5, 305-pounder could still be an effective one- or two-year option. He also has less wear and tear than most players his age would have, as he was a backup for much of his first decade in the NFL. (Kevin Terrell/AP Images)

New England has other options at right tackle, so the Patriots can afford to let Fleming go. After a solid season last year, he should find a steady starting job elsewhere. (Margaret Bowles/AP Images)

The Titans provided a soft landing spot for Kline after he was released by New England just before the start of the 2016 season, and he started all 32 games (including playoffs) in which he played for Tennessee. How well he fits new offensive coordinator Matt LaFleur's scheme could determine whether he stays or moves on in free agency. (Gregg Trott/AP Images)

Slauson heads into the market after his 2017 season ended seven weeks in because of a torn biceps muscle. He had been working at left guard after starting all 16 games at center in 2016. He struggled at times before his injury last season, but he should get a chance to start in what would be his 10th season. (G. Newman Lowrance/AP Images)

Sullivan proved he could make it through a season healthy after battling injuries the previous two seasons, during which he started just one game. The 32-year-old Sullivan also helped provide a steadying influence for Jared Goff and could be a solid option for a team looking to break in a rookie quarterback. (Photo by Peter Read Miller/AP Images)