RB Jordan Mason filled in admirably to start the year, but he was hit with a shoulder injury in Week 6 that he battled until McCaffrey’s return in Week 10. McCaffrey and Mason were both hurt in a Week 13 loss to the Buffalo Bills, which pushed rookie fourth-round pick RB Isaac Guerendo into the starting role.

The San Francisco 49ers are going to have a fourth different starting running back this season according to a report from ESPN's Adam Schefter. Running back Isaac Guerendo suffered a hamstring injury

San Francisco 49ers running back Isaac Guerendo appeared on Wednesday's injury report due to a hamstring issue sustained during last week's game against