That work ethic served him well as he digested McCoy's playbook and fended off Lynch while disregarding the cacophony of Lynch supporters who felt the athletic, agile prospect deserved the job based on potential, not performance.
Those are heady numbers for a guy who once figured football was in his rearview.
Siemian's rise as Manning's surprise successor began when Osweiler jilted the Broncos and left for Houston in free agency 48 hours after Manning retired last year.
"I just worried about myself and improving," Siemian said. "I had a shot coming in and for me, that's all I needed."
Only, he had to reapply, so to speak, when Kubiak stepped down and Joseph arrived.
In the aftermath of those moves, Siemian helped tutor Sanchez and Lynch in Kubiak's system, but when asked if he, himself, felt he had the chance to win the starting job, Siemian said simply: "Absolutely."
General manager John Elway acquired Sanchez in a trade and moved up in the draft to select Lynch, out of Memphis, with the 26th overall pick.
In dispatching Mark Sanchez last season and Paxton Lynch this summer, Siemian has wowed two different coaching staffs while engineering two contrasting offenses.
Reapplying for his job was something Siemian took in stride .
So does Joseph, Denver's rookie coach whose first order of business after replacing Gary Kubiak was to hire Mike McCoy to coordinate his offense and whose second move was to declare his QB job up for grabs in a "50-50 open competition."
That's all he's ever required.
It was an opinion shared by precious few until he went out and parlayed his year's head-start in the offense into the starting job.
Despite missing the offseason program while recovering from knee surgery, Siemian unseated Zac Dysert in training camp as the team's third quarterback. He also forced his way onto the 53-man roster of a Super Bowl-bound team that quickly realized sneaking him through waivers and onto their practice squad wouldn't work.
NOTES: The Broncos claimed DL Jimmy Bean off waivers from the Raiders on Friday, a day after Oakland waived the first-year pro from Oklahoma State who spent last season on the Raiders' practice squad. To make room, the Broncos waived CB Dontrell Nelson.
Siemian is heading into unrestricted free agency after this season, so other teams could get into the mix and push his price higher if he puts up good numbers. The Broncos could also franchise tag him — this year's franchise tag for quarterbacks was worth $21.268 million.
"It was an unbelievable challenge," Siemian recounted last year. "You're forced to kind of make throws and use your imagination a little bit against our guys. I think going against them every day and getting your butt kicked a lot helped a little bit."
Just like Manning used to do.

Although he took just one snap that season,Cheap Jerseys China, Siemian gained invaluable experience listening to Manning and facing Denver's defense.
"That guy wasn't content, Hall of Fame or whatever," Siemian said. "Every day and every week I think you have to earn your job. Quarterback is no different."
Now, the talk is about the unshakable Siemian and how, with a solid season, he could hit the jackpot.
ENGLEWOOD, Colo. (AP) — He's an undersized underdog,Wholesale Jerseys, underpaid and unshakable.
Siemian has dispatched two former first-round QBs the last two summers following a year's apprenticeship under Peyton Manning and Brock Osweiler when he flashed so much in training camp that sneaking him onto the practice squad became impossible,Cheap Wholesale Jerseys.
A sometimes starter at Northwestern, his rather unremarkable resume included a scant 14 starts for the Wildcats with 27 career touchdowns to go with 24 career interceptions when the Broncos took a chance on him.
"I really wasn't expecting a call to be honest with you,Jae Crowder Jersey," Siemian said the day the Broncos made him the 250th overall selection of the 2015 NFL draft.
"It's great," Broncos star linebacker Von Miller said. "I feel very comfortable with Trev."
"That was a huge deal for him being a seventh-round draft pick, being an NFL starter and winning the job two years in a row. That's a tough deal,Wholesale NHL Jerseys," coach Vance Joseph said after declaring Siemian the winner of the five-month audition on Monday.
"Honestly, I think you have to compete for your job every day and every week," he said.
Winning the starting