McNichols was signed to the 49ers' active roster from their practice squad Thursday,
McNichols' promotion comes after he spent Week 15 with the team while Elijah Mitchell tended to a knee injury and was out of action. The former's addition to the active roster would suggest Mitchell is unlikely to suit up Monday against the Ravens, teeing up McNichols for a role similar to Week 15 against the Cardinals that saw him play six special-teams snaps but none on offense.