Eight and counting? A Broncos timeline of QB changes since 2017

ENGLEWOOD, Colo. -- In the wake of a historically dismal offensive performance during Sunday's 20-3 loss to the Buffalo Bills, Denver Broncos coach Vic Fangio is poised to spin the team's quarterback wheel once again.

The Broncos gained just 134 total yards against the Bills, their worst single-game performance since 1992, and Fangio said Monday that pulling quarterback Brandon Allen from the lineup is a consideration after three starts in place of the injured Joe Flacco.

When asked if rookie quarterback Drew Lock could go from injured reserve to starting quarterback this week, Fangio said "it's a possibility."

If Fangio makes the move with Lock, or even throws the wild card of wild cards and gives rookie Brett Rypien a look while Lock waits another week or two, it will mark the seventh different starting quarterback for the Broncos -- and the ninth change overall -- since Week 9 of the 2017 season. That's a span of just 36 games including Sunday's loss.

Here's how those eight changes since 2017 went down and how they looked right of the gate:

Change No. 1: Trevor Siemian to Brock Osweiler in Week 9 of 2017 season.

Why: After a 3-1 start, the Broncos lost three in a row and Siemian had thrown 10 interceptions in seven starts, including three in a Week 8 loss to the Kansas City Chiefs.

How it went: Osweiler completed 19 of 38 passes for 208 yards with a touchdown and two interceptions in a 51-23 thrashing by the Philadelphia Eagles as the Broncos gained just 3.8 yards per play.

Change No. 2: Osweiler to Paxton Lynch in Week 12 of 2017 season.

Why: The Broncos went 0-3 in Osweiler's three starts after he had replaced Siemian.

How it went: Lynch left the game with an ankle injury and was visibly shaken on the bench after completing 9 of 14 passes for 41 yards with an interception in a 21-14 loss to the Raiders.

Change No. 3: Lynch to Siemian in Week 13 of 2017 season.

Why: Siemian completed 11 of 21 passes for 149 yards with two touchdowns in relief of Lynch against the Raiders after Lynch's ankle injury had limited his practice time.

How it went: After an ugly loss in Miami in Week 13 -- 35-9, as Siemian was 19-of-41 for 200 yards and three interceptions -- Broncos won the next two games with Siemian as a starter.

Change No. 4: Siemian to Osweiler in Week 16 of 2017 season.

Why: Siemian left Week 15 game against Indianapolis Colts with a partially dislocated left shoulder (he went to injured reserve) and Osweiler threw for 194 yards and two touchdowns in relief.

How it went: Osweiler threw for 193 yards and an interception but the Broncos didn't score a touchdown until there was 1:18 remaining in a 27-11 loss to Washington.

Change No. 5: Osweiler to Lynch in Week 17 of 2017 season.

Why: It was the final game of what became a 5-11 season, and with Lynch having been the team's first-round pick in the 2016 draft -- they traded up in the round to select him -- the feeling was to toss him back into the lineup to see how it would go.

How it went: It turned out Lynch's start against the Chiefs -- he was 21-of-31 passing for 254 yards with two touchdowns and two interceptions -- was his last of only four starts with the Broncos. The day is better remembered as the first career start for Chiefs' quarterback Patrick Mahomes.

Change No. 6: Lynch/Siemian/Osweiler to Case Keenum before 2018 season.

Why: Siemian was traded to the Minnesota Vikings, Osweiler was not re-signed as a free agent and Lynch was eventually released after the 2018 preseason. Keenum was the Broncos' biggest signing in free agency that March -- a two-year, $36 million deal.

How it went: Keenum played all but one snap in the 2018 season, but looked rattled at times. The Broncos often struggled in pass protection and finished 6-10, were 24th in the league in scoring and Keenum was tied for second in the league with 15 interceptions.

Change No. 7: Keenum to Joe Flacco before 2019 season.

Why: Looking to pump up the downfield passing game, the Broncos traded for the 34-year-old Flacco. Team president of football operations/general manager John Elway said at the time that Flacco "is coming into his prime" and "is a perfect fit for us."

How it went: The Broncos started the season 0-4 and Flacco was sacked 26 times in eight games before he suffered a herniated disc in his neck and went to injured reserve after a last-second loss to Indianapolis in Week 8. After that game Flacco criticized the play-calling as too conservative down the stretch.

Change No. 8: Flacco to Brandon Allen in Week 9 of 2019 season.

Why: Flacco's injury. Flacco said he had dealt with pain in his neck/back "for a couple weeks" before the herniated disc formally ended his season. Allen was a fourth-year quarterback who had waited 42 months between being Jacksonville's sixth-round pick in the 2016 draft and his first start.

How it went: In his first career start, Allen completed 12 of 20 passes for 193 yards with two touchdowns as the Broncos defeated the Browns 24-19. But the Broncos have lost the past two games, scored two field goals in the last six quarters and Allen has completed 46.4 percent of his passes in those three games combined.