"It's simply production on the field," said head coach John Fox. "This is a results business, not a reputation business. Peyton simply hasn't played well in our first two preseason games."
While Manning has zero touchdown passes and three interceptions to go with a 48.8 quarterback rating, Osweiler has a touchdown pass, hasn't turned the ball over and has a 79.9 rating through two games.
"It's been night and day," said Fox. "If they were a little closer, maybe I would have given Peyton the benefit of the doubt or waited another week to make a decision, but there's really no decision to make here. Their performances made the decision. Now we just need to give Brock every opportunity to play with the first team to get ready for the regular season."
Broncos president John Elway is 100-percent behind the decision to bench Manning, who Denver signed to a 5-year, $96 million contract in the offseason.
"Of course I am behind this decision," said Elway. "I think I proved with Tim Tebow that my decisions will not be influenced by fan popularity polls. I want the best quarterback, regardless of fame or jersey sales. And Brock Osweiler is better than Peyton Manning. Anyone can see that."
Osweiler, one of Denver's second round picks, is just the latest young quarterback to be named a starter this week. Jake Locker has taken over the reins from Matt Hasselbeck in Tennessee, while rookie Ryan Tannehill has been named Miami's starter.
The former Arizona State star says he is grateful for the job and hopes to learn from Peyton Manning.
"He may not be good enough to start in this league anymore, but he still knows a lot about football and I can learn from him," said Osweiler. "And maybe he can learn something from me, too, about hard work and dedication and not taking anything for granted. I got the sense he showed up here thinking the job was his. There are no guarantees at this level."