ESPN Fantasy Projection: It's not often you see a running back break out in his fifth NFL campaign, but Mostert did exactly that down the stretch last season. Primarily a special-teams player throughout his career, Mostert put up 859 yards and scored 13 touchdowns on 133 touches during the 49ers' final nine games of 2019 (including the playoffs). An extremely efficient runner, Mostert is averaging 6.0 YPC on 178 regular-season carries for his career, which is easily best among 188 RBs with 150-plus carries. The concerns here are that Mostert plays a minimal pass-catching role (22 targets last season) and Kyle Shanahan is very unpredictable with his backfield rotation. As such, Mostert is best viewed as a flex with RB2 upside.