Allen reportedly will be making way for rookie Drew Lock, who is ready to emerge from Injured Reserve
Lock has taken first-team practice reps all week and all signs point to him starting, according to NFL Network.
Allen has started three games after a season-ending injury to Joe Flacco. Allen won his debut against the Browns, but he has lost his last two, at Minnesota and at Buffalo. He has completed only 46.4 percent of his throws, with three touchdown passes and two interceptions.
Lock, a second-round pick last played on August 19, during a preseason game against the 49ers.
The Broncos host the Chargers on Sunday. A loss by Denver would guarantee a third straight losing season for the Broncos, a feat the franchise last accomplished in 1970-72.
Lock, if he starts, becomes the latest player to drop a coin into the John Elway’s Quarterback machine. With the exception of Peyton Manning and a handful of games from Brock Osweiler, all have failed.