As expected, the Philadelphia Eagles' offensive line was once again ranked as the best in the NFL by Pro Football Focus. The San Francisco 49ers' unit came in at No. 16, which is a four-spot jump from its ranking in 2017.

Pro Football Focus projected the following starting lineup for the 49ers this season, along with their most recent grade:

LT: Joe Staley (87.4)
LG: Laken Tomlinson (70.7)
C: Weston Richburg (71.3)
RG: Joshua Garnett (39.6 grade in 2016)
RT: Mike McGlinchey (90.6 2017 college grade)

The 49ers have good anchors on the outside with Staley and McGlinchey. Offensive lineman Weston Richburg was one of their top free agent targets in March and the 49ers were aggressive in making sure he landed in San Francisco.

The real question marks are at the guard positions. The 49ers signed Tomlinson to a three-year extension in June, ensuring that San Francisco retains his rights through the 2021 season. That commitment makes him a favorite to land the starting left guard job.

"Laken is a very talented player who has improved consistently since joining the team one week before last year's season opener," said general manager John Lynch via a statement following the finalization of the extension. "This offseason, his hard work and dedication paid off as he continued to progress and performed at a high level."

While there is unfulfilled potential with Tomlinson, the 49ers appear to have confidence in him. The story is different at right guard, where Garnett is not only competing for a starting job, but may be fighting for a roster spot. Both Matt Maiocco of NBC Sports Bay Area and Matt Barrows of the Sacramento Bee – soon to be of The Athletic – feel he could be a surprise cut when the team is forced to trim down the roster. If Garnett cannot win a starting job, his future with the team could be at risk.

"If Garnett does not win the starting job, he definitely has less position flexibility than Mike Person, who could serve as a backup at both of the guard positions as well as center," said Maiocco on the 49ers Insider Podcast. "If Garnett does not nail down a starting job, I don't know if somebody else could sneak in there and be considered a more valuable backup. So that would be somebody to keep an eye on for a surprise cut."

"He's going to have to hold off two players the 49ers acquired as free agents, Mike Person and Jonathan Cooper," wrote Barrows. "Person currently is the team's backup center, which seems to dramatically improve his roster chances."

Michael Renner, who bases the 49ers' ranking on that unfulfilled potential, wrote the following for the Pro Football Focus feature:

"Of all the teams on the list, the 49ers have some of the best potential to outplay their current ranking. The reason being unfulfilled potential. Laken Tomlinson and Joshua Garnett are both former first-round picks who have yet to fulfill their potential. Tomlinson took huge strides forward though last season with a career-high 70.7 overall grade while Garnett never got to build on a disappointing rookie campaign (39.6 overall grade) as he missed all last year with a knee injury. Both were highly touted by us here at PFF coming out of college as well. Then you add Weston Richburg – who earned an 86.5 grade back in 2015 – and Mike McGlinchey – PFF's top-rated tackle in the 2018 draft."