The Facts: Though Mostert missed nearly all of the 2021 season with a knee injury, the Dolphins signed him to a one-year deal worth $3.25 million in March. Mostert worked with Dolphins HC Mike McDaniel with the 49ers, so there’s no doubt that Mostert will fit into the scheme. And the running back intends to be healthy for the start of the regular season. “I know his expectations are to play Week One and we are not going to rush it,” McDaniel said in his Tuesday press conference. “He’s come too far to have a setback, so he’s just diligently working day in, day out. But when he’s ready, he’ll be on the field — for sure.”

Diehards Line: Mostert’s knee injury required season-ending surgery. In the last week of the 2021 season, Mostert told 49ers beat writers that his cartilage was damaged enough to leave a quarter-sized hole. The running back added the procedure required a suitable organ donor. Entering the league as an undrafted free agent in 2015, Mostert bounced around before finding a stable home with the 49ers. But he’s battled injuries throughout his career. His most productive season came in 2019 when he counted for 952 yards from scrimmage and 10 total touchdowns. But he then missed half of the 2020 season due to injury. Mostert will have to compete with several running backs for playing time in 2022, including veterans Chase Edmonds and Sony Michel.