Trevor Siemian only played with Peyton Manning for a year, but the quarterback lapped up every bit of information he could from the veteran. And now, in his second year starting for the Broncos, Siemian is showing off what he learned.

DENVER — This is how it was supposed to look, more or less. It wasn’t always pretty or high-flying, but Trevor Siemian got the job done. In his first start since winning the quarterback job for the second season over Paxton Lynch, Siemian was methodical, connecting with seven different receivers on 17 of 28 passes for 219 yards, three scores (two through the air, one rushing) with an interception in a 24–21 season-opening win vs. the Los Angeles Chargers.

Anything less, and you’d have a good chunk of Broncos Nation wondering aloud whether the coaching staff was right to hand the starting gig to a seventh-round pick from three years ago instead of former first-round pick Paxton Lynch.

Was Siemian perfect on Monday night? Hardly. Were it not for Chargers cornerback Casey Hayward’s sudden butterfingers, a first-quarter throw might have gone the other way. And a second-half interception on a batted ball thrown into tight coverage facilitated a Chargers comeback that came down to a missed field goal which would’ve forced OT. If either Hayward holds on or the field goal connects, we’d be having a different conversation right now.

But after his handful of missteps, Siemian, 25, did what veteran quarterbacks do. He forgot about them. Or at least he appeared to in the eyes of his teammates. “That’s the Trevor we know,” Broncos running back C.J. Anderson said. “Calm and collected.”

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Siemian’s apparent popularity in the locker room and current command of the starting job is the latest chapter in a professional journey that began in the summer of 2015, when the Northwestern alum was competing with Zac Dysert for the No. 3 spot on the depth chart behind Peyton Manning and Brock Osweiler. Limited by a knee injury for all of that rookie minicamp, Siemian gave coaches a clue that he might one day soon be the guy in his first interactions with Manning.

“I knew Trevor had a little moxie in one of the first quarterback meetings in the room with him,” says Greg Knapp, Denver’s quarterback coach from 2013–16. “I’ve been around a couple other guys in the room with Peyton who were college free agents or late draft picks, and guys get intimidated. Even for a coach it can be intimidating to be in a room with Peyton. He’ll challenge you, and he’s a bulldog about it.

“I won’t say exactly what he said, but Peyton threw a zinger at Trevor, and it was incredible to hear how Trevor spit one back in Peyton’s face. And I’m going, I love this. Mr. Manning, you’ve got a little bit of a challenge with this rookie. Trevor doesn’t get intimidated easily.”

Siemian laughed at the memory: “That’s funny Knapp remembers that. We had a great room and a good back and forth. Maybe a little too much.”

Siemian beat out Dysert that season, and won a Super Bowl ring as the third-string QB. Osweiler left for greener pastures, signing a four year, $72-million dollar contract with the Texans, only to return to Denver this month after a blip in Cleveland. In the meantime, John Elway, the former Super Bowl winning quarterback, drafted quarterback Paxton Lynch in 2016, only to concede in both ’16 and ’17 that Lynch wasn’t as ready as Siemian.

How big was the gap? Depends on the year and who you ask.

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The original decision to hand Siemian the keys in 2016, coaches say, was a tough one. Lynch had all the physical tools coming out of the draft, and Siemian was still catching up after backing up Manning and Osweiler in ’15. “I think it came down to the wire,” Knapp said. “Paxton’s skillset is really impressive, but he came out of an offense that wasn’t as much of a pro style offense. There’s growing pains there."

And what about 2017? There’s some disagreement. New offensive coordinator Mike McCoy, Manning’s coordinator in 2012 before taking the head coaching job with the Chargers, echoed head coach Vance Joseph in calling it a tough decision. “They all did a great job, all three quarterbacks,” McCoy said. “The great thing about this business as coaches is you’ve got to make tough decisions from time to time.”

But two team sources familiar with the coaches’ evaluation of both quarterbacks said the competition in training camp wasn’t close. Following OTAs, Siemian demonstrated a mastery of the playbook while Lynch lagged behind, the sources said.

If it came down to habits, Siemian benefited greatly from playing behind Manning in 2015, the veteran’s last season. Siemian observed Manning taking copious notes on material simple and complex alike, so he, too, took up the habit and started filling up notepads with concepts he was already familiar with, in chicken scratch handwriting only he could read.

“It’s something I still do,” Siemian says. “Being in the same room with a guy that’s done it really, really well for a number of years. If it worked for him, I figured it might work for me. You process things a little better when you put pen to paper. I still write down too much. It’s just kind of a habit I’ve started myself.”

When Siemian arrived at training camp in a competition with Lynch, he was able to direct teammates on the finer points while Lynch was still putting down a base of knowledge in a new offense. McCoy watched Siemian tutor teammates in meetings with a focus on being accountable to execute assignments on any given play.

“There are days you’re with the ones, days you’re with the twos, and he did a good job of leading in every situation,” McCoy said. “In the meetings he’s great, saying to guys this is what we’re expecting on this play. This is where you need to be in this situation.”

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Fast-forward two months, and there’s Siemian in the opener, barking out pre-snap instructions in the face of defensive alignments he’d never seen before. The Chargers had been careful to show very little in the preseason, and Broncos players say some of the fresh alignments and coverage disguises might have thrown a lesser quarterback for a loop.

Veteran running back Jamaal Charles came away impressed with his quarterback after a third-quarter goal line sequence in which Los Angeles offered an unfavorable look on the edge and Siemian audibled from pass to run, handing off to Charles for a third-and-one conversion that ended a yard away from paydirt.

“It was a great decision,” Charles said Monday night after the game. “I really should have scored. ... The good thing about him is that he’s more of a vet who understands the game. These guys who played with Peyton and are still here, they all have high football IQs.”

These are happy players, knowing that with Siemian, they’re being put in a position to win. And it’s what the staff envisioned when they made the competitive—if unsexy—decision to start him.