The 49ers continue to churn the bottom of their roster after signing Robbie Chosen and releasing Marquez Callaway

And the 49ers might need Abdullah to play in the preseason this year if James misses significant time. Without him, their running backs are Christian McCaffrey, who probably won't play in the preseason, Isaac Guerendo, who is injury-prone, and Corey Kiner, an undrafted free agent rookie. So they need bodies.

The 49ers announced a number of roster moves on Thursday, including the previously reported additions of running back Ameer Abdullah and wide receiver Andy Isabella.