Behind the 49ers' presumptive starting offensive tackles Joe Staley and Trent Brown is John Theus, who played 88 snaps as a rookie last season.
The general belieft is this year’s draft does not hold a bounty of prospects along the offensive line. That would explain why the 49ers made a play Monday to increase depth at a position of need with the signing of restricted free agent Garry Gilliam to a one-year offer sheet.
The Seattle Seahawks have five days to match the reported one-year, $2.2 million contract that includes $1.4 million in guaranteed money.
Gilliam started 29 games the past two seasons at right tackle for the Seahawks. Trent Brown started 16 games at right tackle for the 49ers last season. He won the starting job to thwart Anthony Davis’ comeback attempt with a strong training camp.
But Brown’s play leveled off during the regular season, and with a change to Kyle Shanahan’s offensive system, there is no harm in creating competition for the starting job.
If nothing else, the pursuit of Gilliam could give the 49ers three offensive tackles with significant starting experience.
Gilliam’s time as a starter with the Seahawks appeared to be coming to an end, anyway. Seattle general manager John Schneider told Seattle-area reporters at the recent owners meetings that Germain Ifedi, the team’s first-round draft pick a year ago, would move from right guard to right tackle this season.
Last season, the 49ers’ backup swing tackle was guard Zane Beadles, who started 12 games at left guard, two games at left tackle and two games at center.
The 49ers set out this offseason to increase depth along the offensive line. The team acquired Jeremy Zuttah in a trade with the Baltimore Ravens. Zuttah was a Pro Bowl selection at center last year.
Zuttah can also play guard. The 49ers will have the flexibility to determine if the way to get the best five linemen on the field is to start Daniel Kilgore at center and have Zuttah compete at either guard spot against Beadles or Joshua Garnett.
Meanwhile, Gilliam’s possible addition – the Seahawks would not receive any compensation if they decide to let him walk – would provide the 49ers with insurance at the tackle position.
According to Pro Football Focus, Brown and Gilliam last season ranked near the bottom of the league among offensive tackles who played 60 percent or more of his team’s snaps.
Brown was 46th of 54, and PFF listed him as surrendering six sacks, two quarterback hits and 31 hurries. Gilliam was listed at No. 51 with two sacks allowed, six QB hits and 35 hurries. Gilliam’s run-blocking grade was slightly better than Brown’s, according to PFF’s grading system.