49ers sign Phillip Tanner

AP

During the offseason, there was a lot of talk about how much depth the 49ers had at running back.

The season takes unexpected turns, however, and the erosion of that depth is one of the numerous negative ones that the 49ers’ season has taken this year. Marcus Lattimore retired without ever playing a down, Kendall Hunter tore his ACL, LaMichael James was cut and now Frank Gore and Carlos Hyde are both banged up heading into Week 15.

As a result, the team announced Wednesday that they have signed running back Phillip Tanner. Tanner spent time with the Bills this season when they were hurting for healthy backs, but never saw any game action. He ran 56 times for 149 yards and two touchdowns in 39 games for the Cowboys over the last two seasons.

Gore is recovering from a concussion while Hyde is battling back and ankle issues. Neither practiced on Tuesday as the 49ers began preparing to face the Chargers on Saturday.

The 49ers placed tight end Garrett Celek on injured reserve to open the spot for Tanner.