What if Tyrod Taylor had signed with Broncos, and not Bills, in 2015?

Tyrod Taylor likely would have competed for the Broncos' starting QB job in 2016 had he chosen Denver during free agency in 2015. Timothy T. Ludwig/USA TODAY Sports

ORCHARD PARK, N.Y. -- Tyrod Taylor and Trevor Siemian will walk into New Era Field the same way this Sunday, but the quarterbacks' seasons -- and possibly careers -- seem headed in opposite directions.

Taylor is coming off one of the Buffalo Bills' worst offensive performances in recent memory, a defeat last Sunday in which the Bills gained only 6 net passing yards in the first half. Taylor completed 68 percent of his throws but averaged only 7.35 yards per completion, the lowest output of his 31 games as Buffalo's starter.

Although Bills coach Sean McDermott reiterated Monday he has faith in Taylor and is not considering a change, there has been rumbling from some fans about giving fifth-round rookie Nathan Peterman a look, and a Taylor benching does not seem out of the realm of possibility by season's end.

Meanwhile, Siemian is on the rise. He had more passing yards in the first quarter and a half of the Denver Broncos' 42-17 win over the Dallas Cowboys than Taylor, with 125, had for the entirety of the Bills' loss to the Carolina Panthers. Siemian's four touchdowns Sunday were more than Taylor has ever thrown in a game for Buffalo.

Siemian, a seventh-round pick in 2015 from Northwestern, has held off 2016 first-round pick Paxton Lynch for the Broncos' starting job. Yet had history been different, Siemian's greatest competition might have been Taylor, not Lynch.

The two quarterbacks' paths have diverged since March 12, 2015, the day Taylor decided to sign with the Bills as an unrestricted free agent despite, a source said, being offered a richer contract by the Broncos.

At the time, Taylor had been Joe Flacco's backup in Baltimore. A sixth-round pick out of Virginia Tech in 2011, Taylor had appeared in 14 games for the Ravens. He signed a three-year deal with Buffalo that averaged $1.1 million per season and guaranteed him $1.15 million. The specifics of the Broncos' offer to Taylor are not known.

Taylor signed with the Bills because their quarterback situation offered him more upside. Less than three months after the surprise retirement of Kyle Orton, the Bills signed Taylor to be part of a three-way competition with benched 2013 first-round pick EJ Manuel and veteran Matt Cassel, whom they acquired in a trade two days before signing Taylor. The Bills' contract with Taylor called for his third season to void if he became the starter and allowed for him to earn up to $7 million by reaching incentives.

"I just thought moving forward it was a better opportunity for me to make a name for myself here," Taylor said at the time in reference to signing with Buffalo instead of remaining in Baltimore.

Taylor did not address the Broncos' offer at the time and was not available Monday to speak on the topic, but it is fair to assume Taylor also saw a greater opportunity to make a name for himself with the Bills than with the Broncos.

At least for the 2015 season, the Broncos had an ironclad starter in Peyton Manning, whose 4,727 passing yards in 2014 were the fourth-most in the NFL. But Manning was 39 and nearing the end of his career, and backup Brock Osweiler was entering the final season of his rookie contract.

Gary Kubiak, then in his first season as Broncos coach, had been impressed with Taylor while Kubiak was the Ravens offensive coordinator in 2014. Broncos general manager John Elway is known to have respected Kubiak's opinions on quarterbacks, which made Taylor a target for Denver in free agency.

However, the belief from ESPN Broncos reporter Jeff Legwold is that Taylor would have been the Broncos' third quarterback had he signed. When Manning was sidelined in mid-November of 2015 with a foot injury, he was replaced by Osweiler. That job probably would not have gone to Taylor, according to Legwold.

During the 2015 offseason, Kubiak was high on Siemian, who was recovering from a torn ACL that ended his college career. The Broncos selected Siemian in the seventh round to prevent another team from signing him as an undrafted free agent. Signing Taylor might not have precluded the Broncos from also adding Siemian, although it probably would have pushed the rookie to the practice squad in his first year.

The opportunity for Taylor to start in Denver most likely would have come in 2016, assuming he signed a multiyear deal with the Broncos. In a span of three days in March 2016, Manning retired and Osweiler signed a $72 million deal with the Houston Texans.

Legwold's belief is Taylor and Siemian would have competed for the starting job to replace Manning. The question, had Taylor been signed, is whether the Broncos would have still traded up in the first round that April to select Lynch. It is possible that with Taylor and Siemian, there would have been less urgency for the Broncos to select a quarterback high in the draft.

Boosted by his time learning behind Manning, Siemian impressed coaches during 2016 spring practices and secured the starting job last season. He also earned the respect of the locker room as the scout-team quarterback in 2015, performing well in practice against one of the NFL's best defenses. All-Pro defensive end Von Miller compared Siemian to Peter Parker -- better known as Spider-Man -- for his sneaky ability.

Taylor earned no such nickname in Buffalo but still defeated his competition after signing in 2015. Then-coach Rex Ryan named Taylor the starting quarterback in the days before their season opener, with Cassel traded to Dallas weeks later and Manuel relegated to backup for the next two seasons.

Had Taylor decided to sign with Denver, the Bills' favorite to start in 2015 would have been Cassel. The team might have also pursued another option in free agency such as Matt Moore, who later re-signed with the Dolphins, or have addressed the position in the 2015 draft.

Buffalo was without its first-round selection (No. 19) in 2015 because of its trade for Sammy Watkins the year prior, and even with the pick, they would have had little shot at top quarterbacks Jameis Winston (No. 1) or Marcus Mariota (No. 2). The remaining quarterbacks chosen in 2015 were Garrett Grayson, Sean Mannion, Bryce Petty, Brett Hundley and Siemian. Only Petty and Siemian have started games in the NFL, while Grayson is out of the league.

Unless the Bills took a swing on Siemian, they probably would not have found a better starting option than Taylor. By starting Cassel, who is 36-44 as an NFL starter, the Bills probably would have finished worse than their 8-8 record in 2015, resulting in a higher draft pick in 2016 than the No. 19 selection, with which they took defensive end Shaq Lawson.

At this point, it is tough to call Taylor's decision to sign with the Bills over the Broncos a slam-dunk for him. He received a five-year, $90 million contract extension from Buffalo last August but had that deal largely ripped up while taking a pay cut this spring. Taylor is on his third offensive coordinator, second head coach and second general manager since joining the team, and the current regime has voiced little long-term commitment to him.

The Bills have fallen short of the playoffs each of the past two seasons with Taylor. His hold on the starting job the remainder of the season feels tenuous, and his future in Buffalo beyond this season is uncertain. The second-round pick the Bills acquired from the Rams in stripping Taylor of Watkins this summer could well be used to select Taylor's replacement next spring.

Taylor's signing was a short-term victory for him and the Bills in 2015 and 2016, but the Bills' three-year flirtation with Taylor as a potential franchise quarterback might ultimately be fruitless and possibly have set back the club in finding a more suitable option in the draft. It could also leave Taylor with only backup-role offers if released by the Bills next offseason.

Had he signed with Denver in 2015, Taylor would have served as a backup that season with a chance to beat Siemian for the starting job in 2016. Supported by a Broncos defense superior to the Bills', perhaps Taylor could have led Denver back to the playoffs last season. Or he could have lost the job to Siemian and remained in obscurity.

As for how the Broncos fared without Taylor, not a second thought will be given if the Broncos leave New Era Field on Sunday night as a 3-0 team led by Siemian.