Broncos' Brandon Allen gets his audition at QB while Drew Lock waits

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ENGLEWOOD, Colo. -- When the Denver Broncos claimed Brandon Allen off waivers earlier this season, the 27-year-old quarterback joked his future was "what happens this afternoon."

Understandable for a guy who was been cut three times, spent a season on a practice squad and waited 42 months from the time the Jacksonville Jaguars made him a sixth-round pick in 2016 to his first career start for the Broncos two Sundays ago against the Cleveland Browns.

Allen's fate may depend on the next five games, a stretch that includes four road tests and three teams currently in the league's top 10 in scoring defense.

While Allen's future with the Broncos is uncertain, so is the plan at quarterback. Joe Flacco (neck) is on injured reserve and done for the season while rookie second-round pick Drew Lock is scheduled to begin practicing this week after spending the season on IR (thumb).

Broncos coach Vic Fangio has said he wants Allen to "continue to operate the offense" as he prepares for his second start, against the Minnesota Vikings on Sunday (1 p.m. ET, CBS).

"He's at the point where he knows our offense and he's been in our meetings since he's gotten here," Fangio said. "Now he's getting an opportunity to practice more. Just practice, I think, will produce the improvements we're looking for."

First up for Allen are the Vikings, a team undefeated at home this season, fifth in scoring defense, first in passes defensed and fifth in interceptions. Then it's a road trip to Buffalo -- third in the league in scoring defense -- followed by a home game against the Chargers, who are eighth in scoring defense.

By that time, Lock will have practiced for three weeks and the Broncos will have to decide whether or not to move Lock to the active roster or keep him on IR the rest of the season. Even if Lock moves to the active roster, a start Dec. 8 in Houston or Dec. 15 in Kansas City seems like a big ask for a player who had not practiced since mid-August.

On Monday, Fangio said no decision has been made regarding if Lock would move to the active roster. When asked if Allen's play could impact any decision on Lock in the coming weeks, Fangio said: "That's part of the equation also."

Allen should see plenty of opportunities against the Vikings on Sunday. Minnesota pushed its defensive resources toward the line of scrimmage to stop Dallas Cowboys running back Ezekiel Elliott during a Week 10 victory. That left the Vikings' defensive backs largely in man-to-man coverage. It worked to slow Elliott, who finished with 47 yards on 20 carries, but Cowboys quarterback Dak Prescott threw for 397 yards and three touchdowns.

The Broncos have not shown explosiveness in the passing game, so if the Vikings crowd the line of scrimmage to slow the Broncos' run game -- ranked 16th in the league -- they would essentially be putting the game in Allen's hands. And if you're a quarterback with no career starts in your first three seasons in the league, that's to be expected.

"First of all, Brandon is a very intelligent dude," running back Phillip Lindsay said. "... I was very shocked and surprised when he first got here how well he got the terminology so fast and how confident and calm he is."

Monday, Fangio said the Broncos are in search of more scoring given the team has topped 16 points just three times this season. When asked what he wanted to improve the most in the post-bye part of the season, he said:

"Well, we need to score more points. Was that earth-shattering for you?"