Coach Vance Joseph told his players of the move as the Broncos try to bounce back from a three-game losing streak after Monday night's 29-19 loss to the Kansas City Chiefs that included five team turnovers and dropped the Broncos to 3-4. The Chiefs intercepted Siemian three times and recovered two fumbles.
Osweiler spent his first four NFL seasons with the Broncos and will make his first start for the team since 2015 when he started seven games while Peyton Manning was injured.
"It's my job to do what's best for the football team," Joseph said Wednesday. "Again, when you've lost three games in a row and you've had the turnovers like we've had them -- we're minus-11 -- I think in the last three or four games and obviously (11) total that's not good. If you try to go the same way and it doesn't get better, that's on me."
Siemian has thrown 10 interceptions this season on 152-of-247 passing for 1,669 yards and 10 touchdowns. He is 29th in the league in passer rating (76.8) and has been sacked 25 times.
"I just turned it over, couple of bad decisions, tough to win, tough to beat good teams when you turn it over,'' Siemian said after Monday's loss.
"It's about results and we haven't had them," Joseph told reporters Tuesday. "We've lost three games in a row, and again, (Monday) with four turnovers. At the end of the day, it's about results. It's not about how he's played, it's the end result that we're not getting and it's not good."