What Do the Trent Williams, Alex Mack Signings Mean for 49ers O-line?

The San Francisco 49ers brass appear to do their best work past nightfall. (An inside joke for those who followed along with John Lynch's free agency tweets.)

In the wee hours leading up to the start of the new league year, the 49ers finalized two deals to help bolster one of their biggest questions of the offseason. Outside of the cornerback position, the offensive line appeared to be the most glaring need for San Francisco.

Perhaps one of the biggest question marks was the status of Pro Bowl left tackle Trent Williams. After joining San Francisco in a draft day trade with the Washington Football Team last April, Williams returned as one of the best tackles in the NFL in 2020. The left tackle appeared in 14 games and earned Pro Football Focus' top grade of any tackle in the league, aiding him to his eighth-career Pro Bowl nod.

An elite tackle of Williams' caliber doesn't hit the market often. The 49ers made sure to lock down Williams for the long term, signing him to a record-breaking six-year deal to keep him in San Francisco for the foreseeable future.

Nearly in the same breath, San Francisco managed to shore up the center position. It was reported Weston Richburg, who missed the entire 2020 campaign while working his way back from a torn patellar tendon, would undergo offseason hip surgery, putting his future in question.

Shortly after the report of Williams' re-signing, the 49ers locked down former Atlanta Falcons center Alex Mack. Mack spent the past five seasons in Atlanta, including the 2016 Super Bowl season under then-offensive coordinator Kyle Shanahan. The six-time Pro Bowler also played under Shanahan during his tenure with the Cleveland Browns in 2014. According to PFF, Mack earned a 65.9 overall grade in 2020, the lowest of his career, however, finished the year graded as the 16th-best center across the league. He allowed just one sack in 633 pass blocking attempts last season.

It's not just Shanahan's familiarity with Mack or his experience that made him an ideal free agency target, his durability added another selling point for San Francisco in the free agent market. The center has completed a full 16-game season all but twice over his 12-year career. Prior to missing the final two games of 2020, Mack had played in 90-consecutive starts.

"I'm excited," Williams said of the Mack signing. "Anytime Kyle's offense has been successful, it pretty much starts from the center. The center is the brain trust of our offense and our offensive line. So, to get a guy that's an All-Pro, that's a Pro Bowler that's literally played the position at the highest level you can play it at for as long as he has in the NFL, you can't ask for anything better than that."

San Francisco securing key voids along the O-line could make way for Daniel Brunskill to man the vacant right guard spot. Since 2019, five different players have stepped in at right guard, including 10 starts by Brunskill. Injuries forced the former XFL castoff to spend time at three different positions over his first two seasons in San Francisco. Ahead of the start of the new league year, the 49ers tendered a one-year contract for Brunskill, who was an exclusive rights free agent. He appeared in all 16 games last season at both right guard and center.

With an opportunity for Brunskill to settle in at right guard, San Francisco's offensive line appears set with Williams and Mack adding to left guard Laken Tomlinson and right tackle Mike McGlinchey.

A 2020 opt out, Shon Coleman appears as a leading candidate for the backup tackle role as well as former fifth-round pick Colton McKivitz at guard. The 49ers could also look to fortify depth along the O-line in next month's draft. Initially, several media analysts projected San Francisco selecting an heir to Williams in the first round of the draft. With the 49ers reinforcements secured heading into 2021, San Francisco will have more flexibility with April's 12th-overall pick.