Updated at 10:15 p.m.
SANTA CLARA — Four snaps into the preseason, the San Francisco 49ers lost swing tackle Shon Coleman to a right ankle injury against the Dallas Cowboys. On the next series, Mostert went down with an unspecified injury, and headed to the locker room with a head injury.
Coleman — playing left tackle with Joe Staley and Mike McGlinchey among 28 49ers regulars scratched for the game — was making way on a run to the left by running back Raheem Mostert, when Mostert fell into his right leg. Coleman’s ankle was placed in an air cast as teammates knelt around him, and he was carted off the field.
Following the game, Coleman rested his right knee on a medical scooter, with his lower right leg and foot wrapped in a cast. It’s likely he will be out for the season, testing San Francisco’s already-tenuous offensive line depth.
Willie Beavers replaced Coleman on the field on Saturday, and was less than exemplary. If Coleman is done for the season, it’s likely that rookie Justin Skule could be pressed into duty early as the swing tackle, a role he was drafted to fill, but one San Francisco had hoped he’d grow into.
It’s expected that Skule and Daniel Brunskill will back up the starting tackle spots, but beyond them, there are no other true offensive tackles on the roster. Both Skule and Brunskill — a former tight end who excells at run blocking — need a bit of polish. Brunskill was a practice squad player for the Falcons in 2018 as an undrafted free agent, and spent the early part of this year playing in the now-defunct Alliance of American Football.
San Francisco is already down a center in Weston Richburg and a guard in Joshua Garnett. The 49ers were blasted by injury last season, with running back Jerick McKinnon and quarterback Jimmy Garoppolo tearing ACLs, and placed an NFL-leading $40.4 million worth of salary on injured reserve/PUP/NFI lists.
Mostert was one of San Francisco’s key backs in 2018 after McKinnon went down, rushing 34 times for 261 yards and catching six balls for 25 yards. It’s likely McKinnon starts the season on the injured reserve. Matt Breida was inactive for Saturday, as was running back Jeff Wilson. Two new faces in the crowded running back room — Austin Walter and the newly-acquired Brandon Wilds (who was signed Saturday and was seen working with running backs coach Robert Turner) — were the only two healhty backs left who dressed.