Mostert's projected starting role strengthened after Matt Breida was traded to the Dolphins in a draft-day deal, Eric Branch of the San Francisco Chronicle reports.
Mostert was already expected to be the lead dog in a starting tandem with Tevin Coleman following a record-setting postseason run, but the departure of Breida clears up the backfield picture even more. Jerick McKinnon (knee) still is in the mix after restructuring his contract to stay in San Francisco, but the serious nature of his injury and utter lack of playing time since joining the team will likely land him in a reserve role. Mostert will have the most upside in the 49ers' backfield due to his breakaway speed, while Coleman is likely to provide a decent floor if he continues to get double-digit touches in a shared workload.