The door is open.

Brock Osweiler had slammed the door on Peyton Manning’s return. He conquered the Patriots while battling Tom Brady to a draw. He combined precision with daring.

Manning was done, doomed to spend Sunday afternoons wandering the sidelines while humming that irritating song from his never-ending commercials.

Osweiler opened the door Sunday against the Raiders. The Broncos failed to arrive in the end zone. Osweiler, tentative and nervous, seldom challenged the Raiders’ secondary.

He wasn’t hideous.

But he wasn’t sensational, either, and several million Broncos fans remember Manning when he was sensational.

Those who love the Broncos will be divided. Some side with Brock. Some side with Peyton. Arguments over No. 17 vs. No. 18 will invade our homes. Mother and daughter will shout at each other over Christmas dinner. Friendships will falter.

This could be a lot of fun.

When Manning recovers from his wide assortment of aches, coach Gary Kubiak faces a franchise-altering decision. Does he go with Osweiler, the promising but flawed future of the Broncos? Or with Manning, who might have five or six victories left as his tank approaches its final empty?

Kubiak’s choice will shape this 2015 season. Nothing shakes a football team with the force of a quarterback controversy. Nothing can send a team over the edge like the drama of a locker room divided over the choice of the offensive emperor.

Just look at the 2006 Broncos, who offer a cautionary tale about dumping the old guy for the fresh face who isn’t quite ready for the burden.

In 2005, Jake Plummer led the Broncos to the AFC title game. He was the newly reliable version of The Snake, throwing only seven interceptions. Jake, just 31, seemed ready to direct the Broncos for another five or six seasons.

Mike Shanahan, the fading Mastermind, selected scowling Jay Cutler in the first round of the 2006 draft. Boom. Instant quarterback controversy.

Plummer never recovered from Shanahan’s lack of faith. The precision of 2005 vanished as he returned to the reckless Snake who had once infuriated Cardinals fans. Shanahan benched him in the 11th game, essentially ending The Snake Show. Plummer retired after the 2006 season, ending his career with 161 touchdown passes and 161 interceptions.

The 2006 QB shakeup failed. The Broncos, jammed with talent, failed to ride to the playoffs, and Scowling Jay never carried the team to Plummer-like heights.

Fans endured a similar scenario in 1999. Shanahan dumped the bubbly, popular Bubby Brister for the gloomy, unpopular Brian Griese. The Broncos finished 17-2 in 1998 in John Elway’s final season. They stumbled to 6-10 in 1999 under Griese’s shaky direction.

In the Great Football Debate of 2015, I’m going with Osweiler. Manning is no longer Manning. He should have – for himself and for everyone who cares about him – retired after losing to the Colts in last season’s playoffs. Age had caught him.

Age catches all of us.

The Debate rests in Osweiler’s hands. He was courageous and accurate against the Patriots along with considerable bonus of Elway-level clutch play in the fourth quarter.

The Steelers await. In a stadium on the edge of downtown Pittsburgh, Osweiler will face crowd noise that flirts with levels of an airport runway. He’ll tangle with a surging, mighty opponent.

After the Raiders’ debacle, the door is open to Manning and all the fun and all the pain of a quarterback controversy.

Only Osweiler can save us by shutting the door.