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The most popular quarterback for any struggling team is the one who isn't playing. Or plays behind Alex Smith. Or is on a different team's bench but chatting with your coach and owner before the game. Or playing the final 67 seconds of a blowout loss.

Jimmy Garoppolo's 49ers debut arrived after pocket punching bag C.J. Beathard was finally knocked out late in Sunday's loss to the Seahawks. Garoppolo threw two passes: a fourth-down conversion and a hurry-up touchdown as time expired. His quarterback rating this year is now 143.7, and because he is perfect on fourth downs, in the red zone and against the Seahawks, advanced metrics rank him as the most efficient passer in the history of humankind.

Bengals backup quarterback AJ McCarron chatted with Browns coach Hue Jackson and owner Jimmy Haslam in the end zone Sunday, prompting memories of the ill-fated McCarron-to-Browns trade-deadline fiasco and conspiracy theories about McCarron's future. Jackson later said he only discussed the Iron Bowl with McCarron, an example of what pickup artists call "negging." (Didn't you once lose an Iron Bowl for Alabama, AJ? Now that your self-esteem is shredded, come home with me.) Because Andy Dalton and DeShone Kizer remain the starters for the Bengals and Browns, respectively, McCarron-Browns 'shipping turned out to be the highlight of the Bengals-Browns game.

The Legend of Patrick Mahomes grows with every Chiefs loss and Alex Smith late-game interception. Smith was still an MVP candidate as recently as Columbus Day, when his 11-0 touchdown-to-interception ratio and the Chiefs' 5-0 record made Andy Reid look wise for taking the slow-and-steady approach with his rookie preseason-highlight machine. But Smith currently looks like weak-tea Josh McCown, Mahomes the next Aaron Rodgers.

Anyone who watched Blake Bortles battle Blaine Gabbert on Sunday knows the NFL is facing a severe quarterback shortage. But the next wave of great quarterbacks may already be in the NFL, hiding in plain sight.

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Garoppolo, McCarron and Mahomes, three young quarterbacks with starting potential, made headlines for what they didn't do or barely did Sunday. But they are not the NFL's only prospects-in-waiting. Teddy Bridgewater is trapped behind Case Keenum, who inconveniently refuses to start stinking so we can get on with the comeback narrative. Monday night's game was a reminder of how much fun Deshaun Watson was for the Texans while he lasted.

Add those young guns to Carson Wentz, Jared Goff and Dak Prescott (overreactions to his current slump notwithstanding), toss Brett Hundley and Mitchell Trubisky into the mix (they have had their moments), and sprinkle in a few 2018 rookies, and it's clear the NFL will soon enter a Golden Age in which we never have to watch Brock Osweiler play again once trades and free agency redistribute the quarterback wealth.

Now to throw a whole tub of cold water on all this enthusiasm.

Paxton Lynch.

Nathan Peterman.

Heck: Brock Osweiler. Sixteen months ago, he was Garoppolo or McCarron: the "seasoned" young backup with a few wins under his belt, poised to finally solve his new team's quarterback problem once and for all.

As has long been true, the most popular quarterback for any struggling team is the one who isn't playing. Once he starts playing, all bets are off.

There have already been busts in the search for a new wave of quarterbacks. There will be mistakes and mediocrity as teams comb through Mahomes and Garoppolo types in search of answers. There will also be careers shaped by forces outside each quarterback's control.

That's because good quarterbacks aren't found by scouring benches. They are molded by good situations and organizations. Or stunted and stymied by bad ones.

Take Goff, this season's second-fastest-rising star, and Keenum, the surprise feel-good story of the year. Goff and Keenum combined for 18 interceptions and 49 sacks for a 4-12 Rams team last year.

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Those Rams were coached by Jeff Fisher and his lieutenants/replacements; their offense was a hodgepodge of outdated 1990s ball-control concepts and afterthoughts. Sean McVay replaced Fisher, Keenum landed in a better situation in Minnesota, and suddenly the NFL gained a pair of capable quarterbacks.

Evidence that the system defines all but the best (and worst) quarterbacks is everywhere across the NFL this year. It's in Philly, where an upgraded skill-position corps and coaching staff full of quarterback technicians turned Wentz into an MVP candidate. It's in Dallas, where a few bumps in the road have flattened Prescott's tires. It's in Buffalo, where the Bills learned the hard way that their offense is holding Tyrod Taylor back, not the other way around. It's in Oakland, where a defensive collapse and a coordinator change transformed Derek Carr from a superstar to just another guy.

So instead of wondering who will lead the next vanguard of great quarterbacks, we should really be looking for which coaches and innovators will create the next great systems in which non-Tom Brady-caliber quarterbacks can thrive.

Great coaches and systems may be in even shorter supply than quality quarterback prospects. But there are plenty of places where the perfect quarterback/coach/system synergy could spark.

Kyle Shanahan was an offensive mastermind for 18-and-three-quarter games last year. He lacks the building blocks to surround Garoppolo with talent this year. But he knows what he wants to build.

A smart aleck could point out Reid has developed exactly one quarterback in 19 years. But that quarterback was a pretty good one in Donovan McNabb. Reid manufactures playoff seasons like few coaches in NFL history. Mahomes is in a far better position to succeed than most other rookies of his stature.

Watson will return to a talent-laden Texans roster in 2018, this time with the starting job waiting for him.

Unless Keenum leads the Vikings to a Super Bowl this year, Bridgewater will helm the Vikings in 2018. But in winning seven of the nine games he's started since Sam Bradford's injury, Keenum has set himself up to land on his feet as a premium journeyman for hire.

McCarron may be Browns-bait or Broncos-bait, but the success of McVay and Doug Pederson should make organizations smarter about the quarterback development process. Pederson's staff will get raided for gurus like Frank Reich and John DeFilippo. Teams will invest in veteran receivers and sure-handed tight ends to act as security blankets for developing passers.

Stodgy John Fox-like coaches and their "game manager" types are about to go out of style. Here come the run-pass options, audibles beamed directly into helmets and systems tailored to the guys running them, not the other way around.

The best scouting reports on Garoppolo and McCarron are more than a year out of date and based on a few dozen passes. As a college prospect, Mahomes looked like a guy who would throw four touchdowns and five interceptions per week. Watson had plenty of ups and downs when you look beyond the hype. Bridgewater is a folk hero in our grainy memories but looks more like Alex Smith on the stat sheet.

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Even NFL personnel evaluators (the unassailable experts who let Keenum drift on the waiver wire while passing Osweiler like a hot potato and engaging in a Mike Glennon bidding war) do not know which, if any, of these quarterbacks will emerge as a star.

But the next wave of great quarterbacks will not be discovered. It will be developed. And there are plenty of prospects who only need the right opportunity.

Teams just need to start fixing problems instead of fixating on finding the perfect passer. Because the only perfect quarterback is the one who hasn't played more than a minute yet.

Mike Tanier covers the NFL for Bleacher Report. He is also a co-author of Football Outsiders Almanac and teaches a football analytics course for Sports Management Worldwide. Follow him on Twitter: @MikeTanier.