When Mike Glennon signed with the Bears in mid-March, he never could have imagined the scene that would unfold in front of him outside Halas Hall last week. After four seasons with the Buccaneers—the final three of which he spent as the backup—the 27-year-old agreed to a deal with Chicago this offseason that included $18.5 million guaranteed and presumably made him the team’s starting quarterback. But there he was on August 23, barely three weeks out from from a Week 1 matchup with the Falcons, answering questions about another passer.

Before practice that day, Glennon had been informed that Mitchell Trubisky, the rookie the Bears took with the second overall pick in the 2017 draft, would get his first reps with the starters in advance of playing a series with them in a preseason game against the Titans. When asked whether this added to the challenge he faced by playing in front of a first-round passer, Glennon was candid. “Yeah, I’d be lying if I said it’s not part of it,” he told reporters. “That’s kind of what I mentally prepared myself for going into this, having gone through a situation with a high draft pick.”

Two years into his tenure with the Bucs, Tampa Bay drafted Heisman Trophy winner Jameis Winston with the first overall pick. After spending the first stage of his career in the shadow of a top-two pick, Glennon now lives with another looming behind him.

As Glennon fielded questions, Trubisky stood on the far practice field less than 100 yards away, throwing passes while Peyton Manning and offensive coordinator Dowell Loggains looked on. Since retiring from the NFL after the 2015 campaign, Manning has made visits to plenty of different teams, but it’s unlikely that the five-time MVP has regularly had reason to show much interest in an organization’s ostensible backup.

Almost nothing about this situation is typical, though. Not long after Glennon left the podium, Trubisky took his place in front of the group of assembled reporters. The 23-year-old rookie did all he could to prevent speculation, offering up quotes like, “The quarterback room’s great; I think competition brings out the best in everybody,” and, “You guys aren’t going to get any crazy answers out of me.” But no matter how much he attempted to downplay the developments, the Bears had already ensured that their quarterback competition would be a subject of endless fascination. By maneuvering to draft Trubisky with the no. 2 pick in April, Chicago’s front office made its intentions clear: It’s not a matter of if he will ascend to the starting job; it’s a matter of when.

Using a placeholder quarterback while a potential star waits in the wings used to be a common occurrence in the NFL, but it’s recently become far less frequent. Of the 26 quarterbacks taken in the first round since 2007, only six have started fewer than six games as rookies, and that list is not inspiring. Yet this year could be an exception. With Trubisky entering the season behind Glennon in Chicago, Patrick Mahomes II sitting behind Alex Smith in Kansas City, and Deshaun Watson backing up Tom Savage in Houston, all three quarterbacks drafted in the first round in 2017 are set to begin their careers on the sideline.

That dynamic has become a rarity, and for the players who’ve previously served as both a team’s quarterback of the (near) future and (temporary) present, the experience left a lasting impression.

Before arriving in San Diego as a rookie in 2004, Philip Rivers had never been a backup quarterback. From 2000 to 2003, he was a four-year starter at North Carolina State who blossomed into one of the most prolific (13,484 passing yards) and seasoned passers in NCAA history. When he finished his career with the Wolfpack, he’d attempted more throws than all but three college players over the past half century. But with Drew Brees entrenched as the Chargers starter, Rivers spent his first two NFL seasons holding a clipboard. “The jarring thing, maybe the toughest thing, was getting used to putting in the work during the week, preparing, pulling into the stadium, watching the game, and going home,” Rivers says.

For Rivers, Aaron Rodgers, and Carson Palmer—who all were first-round picks and sat as rookies—transitioning from having a constant impact to having none defined their rookie campaigns. “What’s different is that you’ve been playing on the field for a long time, so the routine and the expectation is, ‘Oh, there’s a game? I’m playing,’” Rodgers says. “You have to kind of get used to that.”

Beyond reaching that realization, the task for any young quarterback is finding ways to improve without the benefit of much live-action work. Palmer, who sat behind Bengals starter Jon Kitna after being selected first overall in the 2003 draft, says that in a given 70-play practice that year, he was lucky to get 15 snaps. As Kitna went through plays, Palmer would look on and try to replicate the veteran’s thought process and progressions. For Rodgers, the most important X’s-and-O’s work in his time as a backup came while studying tape of Brett Favre and Tom Brady. “I focused on the head a lot,” Rodgers says. “Where their head was looking pre-snap, at the snap, and post-snap. Because it’s so important to think about those things, as far as eye control, eye discipline, and route concepts—looking people off and throwing people open.”

“Every once in a while you go, ‘Hold on. Why am I thinking about golf?’”

—Carson Palmer

Both Palmer and Rodgers still espouse the value of those mental reps, but that doesn’t mean they found it easy enhancing their games. Going from a starting to a backup role means moving from getting constant feedback to watching someone else get most of the coaches’ attention. Staying engaged requires a new level of discipline. “That was a good test,” Palmer says. “Every once in a while you go, ‘Hold on. Why am I thinking about golf?’ So you dial back in. It was a good training exercise to try to keep that focus for a three-hour practice.”

Rivers says that the pro game was fast and new enough early on that he didn’t mind his place on the sideline. Eventually, though, watching from afar started to have diminishing returns. He sees the same phenomenon now when he works with young quarterbacks. Explaining the decisions a passer should make is rarely a replacement for learning on the fly. “It’s like we say when we watch film: ‘I think I would have thrown it there [instead],’” Rivers says. “Well, yeah, I’ve got the rewind button in my hand. You have to experience it. There’s no substitute for actually doing it.”

Around Week 10 of his rookie season, Rivers felt his development stall, which made his second year behind Brees in 2005 increasingly frustrating. “I felt like it was putting along,” Rivers says. “Like, can you have great growth when you continue to do this?”

There may be a limit to how much a newcomer can learn about playing quarterback without getting on the field, but learning how to be a QB is a different story. Palmer and Kitna, for instance, were close from the moment the former was drafted out of USC. During training camp in Georgetown, Kentucky, the pair played golf every day after practice. Spending time around Kitna allowed Palmer to adopt productive habits. “I didn’t know how to take notes,” Palmer says. “I didn’t know how to watch film. I had been watching myself forever. So just seeing how he’s writing clues to himself for certain coverages and tips on certain pressures [was valuable].”

Palmer also derived value from observing the way Kitna interacted with teammates, a lesson Rivers learned while studying Brees. “I want to get to know these guys, to earn some trust and respect,” Rivers says. “So if it goes this way [because of an injury], then it’s already, ‘We’re good with him.’”

In pursuit of a similar takeaway, Rodgers says that he would even poke his head into the huddle—more often during his second year than his first—to hear how Favre would call certain plays and what language he would use. “All that stuff helps,” Rodgers says. “You have to have, as a starting quarterback, not only a great grasp of the offense but you have to kind of know who you are, too, to have that charisma, that likability. And that grows as you understand your role on the team.”

Jake Plummer was at his cabin near Coeur d’Alene, Idaho, during the 2006 NFL draft. Three months earlier, he’d closed out his third season as the Broncos starting quarterback with a 34-17 loss to Pittsburgh in the AFC championship game. To that point, he’d gone 32-11 as Denver’s starter, including a 13-3 finish in 2005 that propelled Plummer to his first Pro Bowl. There were times during that year’s playoffs when he envisioned winning Super Bowl MVP honors and riding off into the sunset after a nine-season career. When that dream crumbled against the Steelers, though, the then-31-year-old was game for one more ride. “I was all in,” Plummer says. “I wasn’t half in, half out. I was in for one more year and ready to do it. It wasn’t like I didn’t want to play. I did.”

Plummer wasn’t glued to the TV during the draft, so when the Broncos traded up four spots and used the 11th overall pick on Vanderbilt quarterback Jay Cutler, Plummer’s brothers were the ones to tell him. He tried to explain that players aren’t privy to the front office’s decisions. “Whatever he was coming out of college, whatever they saw in him, that’s the powers that be,” Plummer says. “That’s not in my control.”

Plummer figured Broncos head coach Mike Shanahan had an inkling that his veteran passer was nearing the end. A decade into his career, Plummer had little patience for Quarterbacking 101; he knew defensive fronts and didn’t see the need to linger at the facility for hours to study. “I took it more as an affront to the whole team,” Plummer says. “Instead of addressing our needs—which, we had me at quarterback—we drafted a rookie in the first round rather than pick someone up to develop in a year or two and get a badass D-end or a game-breaking receiver.”

When teams draft a quarterback in the first round, there’s rarely an assumption that the entrenched starter will become a mentor. Still, most in the scenario take on that role. Plummer says he was no different. “I did my better part to help Jay become the best he could be and impart whatever knowledge I had on him.”

Matt Hasselbeck stepped into a drastically different situation when he signed with the Titans in 2011. That year’s lockout meant that Tennessee had already drafted Jake Locker eighth overall when free agency opened. “They basically said, ‘Listen, we love what happened with Aaron Rodgers, the fact that he sat and waited,’” Hasselbeck, now an ESPN analyst, says. “‘Whenever he was ready, that’s when they threw him out there. And we would like [the same thing]. We’d like to go at Jake’s pace.’”

Hasselbeck wasn’t expected to show Locker the ropes, but he told Locker that quarterbacks from his past had served that role that for him, and he planned to do the same. “It’s more fun when you kind of have a competitive environment,” Hasselbeck says. “I remember Brett Favre even said it one year. He said, ‘I want y’all to compete with me every day and make me better.’ I was like, ‘Wait, what did you say? How am I going to make you better?’ But the fact that he said it [mattered].”

Hasselbeck’s and Plummer’s experiences being a placeholder quarterback diverged once games started, too. Hasselbeck lasted an entire season as Tennessee’s starter before Locker was handed the keys to the franchise, and he still feels that ownership was too impatient with its prized draft pick, especially after two of Locker’s draft mates—Cam Newton and Andy Dalton—had successful rookie campaigns. “They put him out there, in my mind, too soon,” Hasselbeck says. “It wasn’t good for him.”

Denver, meanwhile, started the 2006 season 7-2 with Plummer under center, but following a 35-27 loss to the Chargers in Week 11—in which Plummer went 13-of-28 passing for 183 yards with an interception—the rumblings about a switch started to intensify. After the Broncos scored only 10 points in a Thanksgiving defeat to the Chiefs, Plummer was called into Shanahan’s office and told he was being relieved. “The seeds that were planted right after the draft, those are the ones that are tough,” Plummer says. “Because those grow, and they’re fed by people in the building. Those articles get out there, and the fans start feeling like they know everything going on. Every incomplete pass [was] like, ‘Ah, Jay Cutler would have completed that.’”

“Guys were pissed off at me. I’d be drinking beers, and they were just like, ‘You suck, man.’ Well, they benched me. It wasn’t my decision, so I’m having a Bud Light.”

—Jake Plummer

Plummer used the final month of that season to soak in the quieter moments of life as an NFL quarterback. He saw it as a chance to eat actual meals before games again, and during pregame warmups he would play “football golf” with practice squad quarterback Preston Parsons, kicking the ball toward a target and counting the strokes. On Saturday nights, he’d dig into the beers left out in the hotel for coaches. “I’d sit there and have three or four pops,” Plummer says. “Guys were pissed off at me. I’d be drinking beers, and they were just like, ‘You suck, man.’ Well, they benched me. It wasn’t my decision, so I’m having a Bud Light.”

He doesn’t blame Cutler. It wasn’t his decision. But where some of these quarterback transitions, from Palmer supplanting Kitna to Locker taking over for Hasselbeck, unfolded naturally, this one showed what can happen when the groundswell that comes with drafting a first-round quarterback takes over. “The situation wasn’t pretty,” Plummer says. “It wasn’t a good way to end my career. But I had a lot of fun those last five weeks being the backup and just kind of enjoying what I did.”

As Palmer reflects on the benefits and drawbacks of his redshirt rookie season, he makes clear that there’s no tried-and-true blueprint in these cases. Every situation depends on a multitude of factors. Cincinnati, for example, finished 8-8 in 2003 and narrowly missed the playoffs; even if getting tossed to the wolves might have helped his own progress, Palmer knows Kitna was the better choice for the team that season. “I think there were definite benefits [of sitting],” he says, “but I also know the benefits of getting thrown in there, of having to struggle and learn your way.”

In Palmer’s mind, the structure with Mahomes and Smith in Kansas City is “an ideal situation to be in,” with a gifted but undeniably raw quarterback learning from a veteran who’s played in a half dozen offensive systems during a 12-year career. “Trubisky with Glennon, it’s tougher,” Palmer says. “Because Glennon’s been there for a couple months. He doesn’t have a ton of starting experience.”

“My hope for those guys is that they can come along at their own pace. I did, and it meant the world to me.”

—Aaron Rodgers

Rodgers points out that his experience in Green Bay was unique. Few quarterbacks taken in the first round ever get to play behind a legend like Favre and are spared any sense of impatience from within their organization. Independent of the names involved in this year’s quarterback succession plans, though, Rodgers would like to see this rookie crop learn the league and their place in it at the proper rate. “My hope for those guys is that they can come along at their own pace,” Rodgers says. “I did, and it meant the world to me. Not everyone is in a situation where they’re playing behind a first-ballot Hall of Famer, but to be able to come along without that pressure allows you to reset.”

That reset is a chance to step out of the constant high-pressure demands placed on a starting quarterback. After spending years in the churn of week-to-week preparation, getting that time on the bench allowed him to take a longer look not only at who he was on the field, but also at what the league was like. “If you’re smart, and you listen, and you watch, you can start to figure out how these guys make it—and why other guys don’t make it,” Rodgers says.

This class of someday QBs will get that opportunity only if their respective franchises show a measure of self-control. In Kansas City, head coach Andy Reid has said at every turn that Smith will be his 2017 starting quarterback. “There’s no gray area to that,” Reid told reporters last week. Bill O’Brien has made a similar decree in Houston, and for the Bears, it appears as though Glennon’s solid outing in his preseason finale against the Titans has allowed him to hold off Trubisky, at least for now.

“When you’re trying to wonder what someone is going to do at the quarterback position, young quarterback or old quarterback, you should look at when the GM or head coach’s contracts are up.”

—Matt Hasselbeck

Yet ask the veteran quarterbacks who’ve lived this reality and they know how quickly those winds can change. “When you’re trying to wonder what someone is going to do at the quarterback position, young quarterback or old quarterback, you should look at when the GM or head coach’s contracts are up,” Hasselbeck says. “That’s when they want to be hitting their stride, not starting over.” Reid got a new deal with the Chiefs in June, but the timelines for the head coaches in both Chicago and Houston are considerably shorter.

Plummer knows that with so many components influencing the men in charge, it doesn’t take much for a team’s preference to change. “The doubt was cast,” he says of the Broncos drafting Cutler. “That’s the bad part, when that happens. That’s the hard part for a QB to adjust to. Now everything you do, there’s going to be somebody out there paid to write an article saying, ‘Is it time to make that switch?’ Whether the guy behind you is ready or not, it doesn’t matter.”