49ers' McCaffrey and Mason sidelined with injuries, placed on IR

The San Francisco 49ers are placing running backs Christian McCaffrey and Jordan Mason on injured reserve following injuries sustained in a loss to the Buffalo Bills. McCaffrey, who has a PCL injury, will miss the rest of the regular season, while Mason is sidelined with a high ankle injury. With both players out, rookie Isaac Guerendo will become the lead tailback, and the team may promote Patrick Taylor Jr. from the practice squad. The 49ers, currently 5-7, face a challenging path to the playoffs.