Mostert (knee) was shifted from the reserve/COVID-19 list to injured reserve Tuesday.
Since getting hurt in Week 1, Mostert underwent an October procedure to address chipped cartilage in his left knee, was cleared to walk without crutches Dec. 12 and then spent much of January on the COVID-19 list. There's no chance the seven-year pro returns from IR this season, but he appears as if he'll be healthy at some point between the end of the 49ers' season (whenever that may be) and the offseason program. In the meantime, rookie sixth-rounder Elijah Mitchell will continue to lead the backfield.