ORCHARD PARK, N.Y. — With 4:55 remaining in the third quarter Sunday, Brandon Allen faked a shotgun handoff to Phillip Lindsay, who moved to his left, then faded and threw off his back foot to Royce Freeman in the right flat.

Freeman looked like he had the corner, but Bills linebacker Matt Milano took care of that, bringing him down at the Denver 20-yard line.

It was a forgettable 2-yard gain.

Except that it was also the end of the functional phase of Allen’s work in a 20-3 loss to the Buffalo Bills at New Era Field on Sunday.

The rest of the afternoon was not even zero. It was less than that.

Ten pass plays.

Eight incompletions.

Two sacks for 19 yards in losses.

An average of minus-1.9 yards per pass play.

All that was missing from the dreadful end to the game was an interception or two. Allen and the Broncos can thank the Bills for that. Taron Johnson and Tre’Davious White each dropped passes that could have resulted in pick-sixes.

But in the second quarter, Allen had already thrown an interception in the red zone on a pass to Courtland Sutton — one that Allen admitted was his fault, as he didn’t realize that Sutton would break off his route, setting up an easy theft for White.

Allen and the Denver offense were as miserable as the weather conditions.

The Broncos finished Sunday with their lowest output in total offense (134 yards) since Oct. 12, 1992 and their worst passing day (49 yards) since three weeks earlier in that same campaign.

Think about what that means.

Through the Shawn Moore/Tommy Maddox alternating-play platoon, through spot starts for Bill Musgrave, Jarious Jackson and Chris Simms, through Tim Tebow and Paxton Lynch, the Broncos never passed for as little yardage or gained as few total yards as they did Sunday.

The last time their passing game and offense was this immobile, 34 of the 53 players on the Broncos’ current roster were not even born.

So what reason is there to not play Drew Lock?

Giving Allen another opportunity certainly isn’t a reason to sit Lock. It’s doubtful that the second-round pick would have fared much worse in Buffalo’s blustery conditions. He probably would have done better, as his arm strength would have likely allowed him to push passes through the gusts that Allen could not.

And to start Brett Rypien next Sunday would be to turn one’s back on the work of the preseason and training camp, when Lock was ahead of Rypien on the depth chart — and the since-released Kevin Hogan, too.

Only fear of the unknown and fear for the long-term effect it could have on Lock’s development would prevent the Broncos from putting him in the starting lineup next Sunday.

But as Broncos coach Vic Fangio noted last Wednesday, there is no use worrying about the game being too big for a young quarterback.

“I don’t worry too much about him getting overwhelmed,” Fangio said then. “Some people [will say], ‘Well, he can get overwhelmed and then his career is scarred.’

“If a guy gets scarred from some bad performances, whether they’re all his fault or it’s the team’s fault, then he probably wasn’t the guy you wanted anyway.”

Bingo.

You take the five games to learn about Lock. To learn what he can handle. To find out how he grasps the offense, commands the huddle and responds to adversity.

He is the unknown, yes.

But the known of the last three games with Allen is a quarterback who is a potential backup, and nothing more — and also a quarterback whose production is in free fall.

Allen’s week-to-week pattern tells all:

Passer ratings

• Week 9 vs. CLE: 125.6
• Week 11 at MIN: 61.9
• Week 12 at BUF: 32.4

Yards per attempt

• Week 9: 9.7
• Week 11: 6.2
• Week 12: 3.3

Completion percentage

• Week 9: 60.0
• Week 11: 43.6
• Week 12: 40.0

TD-to-INT ratio

• Week 9: 2-0
• Week 11: 1-1
• Week 12: 0-1

Allen’s numbers are declining faster than a big-box retailer’s stock price.

Those games, piled onto a preseason body of work that includes a 6-to-11 touchdown-to-interception ratio and an 70.9 passer rating in the equivalent of roughly seven games of work, should be enough to show the Broncos what they have in Allen.

What’s more, consider this: Allen has completed 46.4 percent of his passes since he ascended to the Broncos’ starting role.

According to pro-football-reference.com, that is the worst completion percentage of any of the 137 quarterbacks to throw at least 75 passes in regular-season or playoff games since 2010. Worse than forgettable names such as Ryan Lindley and Nathan Peterman.

And yes, worse than Tebow.

The Broncos know what they have in Allen.

Thus a decision would come down to Lock and Rypien — and Lock beat out Rypien for the No. 2 job in the spring and summer.

There is no reason to wait any longer.

It’s time to celebrate Locksgiving and make the next month Drewcember.