Allen (coach's decision) is inactive for Sunday night's contest against Buffalo and will be the 49ers' emergency third quarterback, Matt Barrows of The Athletic reports.
Allen will drop to the No. 3 role at quarterback in Week 13 after completing 17 of 29 passes for 199 yards with a touchdown and an interception in the team's Week 12 loss to the Packers. Joshua Dobbs will operate in the backup role behind Brock Purdy versus the Bills.