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SAM BRADFORD APPEARS to be the least subversive player in the NFL. He runs between practice drills in his red jersey like a JV player trying to impress his coaches. He drives a lifted Ford F-150, the same model he's driven since entering the league in 2010 -- also the vehicle known for being the most popular in America. "Yep, that's all I drive," he says with a shrug. Even his attempts at exuberance can go wrong. After throwing for his second touchdown in the Vikings' Week 5 win over the Texans, Bradford celebrated by jumping into the chest of Alex Boone and promptly bounced off the 310-pound guard like a finch flying into a window.

But perhaps the most Bradford thing about Bradford? The long, floppy sleeves that make it look as if he's wearing a jersey that has to be returned to the equipment shed at the end of the season. When his name is announced before games at U.S. Bank Stadium, he jogs out of the Viking-ship facade without so much as a fist pump. Slow and steady, he is nothing more than a guy who's been told where to go and is intent on getting there unnoticed, as efficiently as possible.

When asked whether anything interesting happened to him over the past five months, Bradford says, "Been pretty boring, to be honest with you. Nothing really comes to mind." He plays it straight just long enough before issuing a wide smile that reaches his eyes a beat or two later. "It's phenomenal how he's mastered the art of saying nothing, but in a friendly way," Boone says. "I love it."

This man, whose unobtrusive personality has meshed perfectly with the impact he has made since being the No. 1 pick in 2010, is leading the offense for the last unbeaten team in the NFL. This man, whose career is distinguished by punctuation -- question marks for the time he's been on the field, commas for the vast amount he's missed to injury -- is authoring the type of personal renaissance that is already triggering a reconsideration of himself and the most glorified and overanalyzed position in sports.

It began when Bradford was traded from the Eagles to the Vikings after Teddy Bridgewater suffered a horrific knee injury less than two weeks before the regular season. The trade followed an offseason that did nothing to enhance his reputation. Bradford signed a contract extension in Philadelphia, saw the Eagles trade up to draft Carson Wentz at No. 2 overall and then held himself out of voluntary offseason workouts in what was described by America's sports media as either the "dumbest" or the "most pointless" leverage-free holdout in history.

Despite the turmoil, and despite making it known after the draft that he wanted to be traded, Bradford didn't anticipate being a possible replacement for Bridgewater. "Honestly, I should have," he says, "but they didn't want to trade me in the spring, so I figured they weren't going to trade me a week before the season."

After playing in five schemes over six years in St. Louis and Philly, Bradford has finally found success under Vikings offensive coordinator Norv Turner (right). Minnesota Vikings

In Minnesota, Bradford got a crash course in coordinator Norv Turner's offense, started against the Packers eight days after he arrived and has only gotten better since. Through four starts, he was seventh in the NFL in Total QBR and second to Atlanta's Matt Ryan in passer rating among quarterbacks who had thrown at least 100 passes. Air-dropped into a new offense just before the season opener, he has not thrown an interception.

In fact, Bradford's resurgence makes him the perfect subject to explore the cult of the quarterback, the cottage industry that's grown up around the idea that an NFL playbook is the sports equivalent of the Human Genome Project. How could he possibly grasp the convolutions and minutiae of an NFL offense, one devised by a legendary offensive coach, in just two weeks?

Presented with this, Bradford suddenly turns subversive. He answers silently, with a cartoon eye roll, then says, "I learn a new system every year anyway."

ON SEPT. 3, a Saturday, Bradford and his wife, Emma, were taking advantage of a rare weekend without football to do some fishing in Oklahoma. At 8 a.m., Sam received a call. Eagles coach Doug Pederson was on the line, informing Bradford he'd been traded to the Vikings. By 1:30 that afternoon, Bradford and his wife were on a private jet heading for Minneapolis, and two hours after that Sam was sitting in a meeting with Turner and his son, Scott, the Vikings' quarterbacks coach.

"There's no magic formula," Scott Turner told Bradford. "We've got to attack this thing. We're not going to ease into it. We're going to throw a bunch of stuff against the wall and make it stick."

Starting the next day, Bradford arrived at the team's practice facility each morning at 6 to learn the terminology of the offense. At 7 a.m., Scott Turner would spend an hour showing him PowerPoint presentations of formations and pass routes before the regular quarterbacks meeting. From there, Bradford sequestered himself with film study before practice. After practice, Scott would summon a few low-level coaches -- or just "random people," as Bradford puts it -- to run routes on the practice field. After that, Bradford and Scott would go back into the building and review video cutups of the plays they'd just walked through. Other times they would set up Bradford with a virtual reality headset, called STRIVR, to give him real-time simulations.

"It's like someone parachuted you into Mexico. You know what a banana is, but you have no idea what they call it." Vikings quarterback coach Scott Turner, on the difficulty of learning a new offense on the fly.

"Sam's obviously a very smart guy, but it's also him basically living in here," safety Harrison Smith says. "Every time I was in here, he was always in here. If we were off, he was here. I honestly don't know how much he left the facility when he first got here."

Bradford, typically understated, says he spent an average of 14 hours at the facility before going home to eat dinner and study more film. "I don't know if I ever came up for a breath over those two weeks," he says. "Definitely crazy."

Running back Matt Asiata says, "When he first got here, I looked at Sam and thought, 'This guy looks like a smart guy.' He has to be. Norv's offense is pretty ... let's say it's Spanish sometimes."

Still, Bradford cautions anyone from making too much of his achievement. "To me, you can pretty much learn anything," he says. "I've run pretty much all these concepts somewhere in my career. The concepts aren't all that different, but the small details within the concept might be different."

The way Bradford explains it, the hard part is compartmentalizing words that have different meanings in different schemes. Let's say green means one thing in Philadelphia and something entirely different in Minnesota. When faced with green in Minnesota, he has to translate it from the previous language. "OK, what hits my brain?" he asks himself. "But over time, that fades out and this becomes your language. This is what you understand, so when you hear these playcalls, you get it."

When Teddy Bridgewater shredded his knee, Bradford rescued the Vikings' QB situation, learning the offense in just two weeks. Adam Bettcher/Getty Images

Scott Turner told him, "It's like someone parachuted you into Mexico. You know what a banana is, but you have no idea what they call it."

Normally, a quarterback -- even a quarterback who has gone through three regime changes in three years, as Bradford has -- is provided with at least an offseason to learn the new language. In Minnesota, Bradford had just two weeks.

"He doesn't know much about us, so he's just finding the open guy," receiver Adam Thielen says. "The way it happened so fast, there was no other choice but to trust us."

LESS THAN FOUR minutes into the Vikings' rout of the Texans, Thielen runs down the right sideline and puts a double move on cornerback Johnathan Joseph as Bradford releases the ball. When it spins off his fingertips in a geometrically precise arc, its outcome as obvious as its spiral, you know precisely why he was chosen No. 1 in 2010. And as it lands in Thielen's hands, as if dropped there by a gentle wind, for a 36-yard touchdown, you know why the Vikings gave up a first-round pick in next year's draft and a conditional fourth in 2018 to get him to replace Bridgewater.

Those who believe in Bradford do so despite his past, despite his injury history and despite an undercurrent of skepticism about his "mental toughness." He missed the entire 2014 season after injuring his knee midway through 2013 and re-injuring it in preseason. He threw for more than 3,700 yards in Chip Kelly's offense in Philadelphia last season, but 19 touchdowns and 14 interceptions left critics unconvinced. Of the six quarterbacks taken with the No. 1 pick since QBR became a measurement of a quarterback's worth, only the infamous bust JaMarcus Russell had a worse rating than Bradford's 49.8.

But is it possible that quarterbacks aren't out there by themselves?

Minnesota's offense, after losing Adrian Peterson in Week 2, employs more of what Bradford does best: working out of the shotgun, throwing short, quick passes to make up for the NFL's worst rushing offense. In leading Minnesota over the Texans to go 5-0, Bradford was 22-of-30 for 271 yards and two TDs. But to get a clear view of Bradford's resurgence, you also have to look to the other side of the ball. The Vikings' D, fast and nasty, is allowing an NFL-low 12.6 points per game. (By comparison, the Eagles allowed 26.9 a year ago.)

Bradford signed a contract extension in Philadelphia, then saw the Eagles trade up to draft Carson Wentz. He then held himself out of voluntary offseason workouts, which did nothing to enhance his reputation. Jonathan Newton/The Washington Post/Getty Images

As for the persistent suggestions that Bradford has lacked mental toughness, that causes Vikings tight ends coach Pat Shurmur's eyes to flash and his voice to rise. "That's so far from the truth," he says, leaning into the words. Shurmur was Bradford's offensive coordinator in his rookie year in St. Louis, then again last season in Philadelphia. He repeatedly says he felt "responsible" for Bradford in both places. In Minnesota, he was Bradford's most vocal advocate when the trade was being discussed. "He got injured, and sometimes there's nothing you can do about that," he says. "Along the way, he's taken some hits and matured as a pro. Not mentally tough? That's the furthest from the truth when you talk about Sam. He's tough as nails."

"Not mentally tough? He's tough as nails." Vikings tight end coach Pat Shurmur on Bradford

"I really think he's a different guy here," Boone says. "I think he's more confident, more comfortable. I think he's not afraid to let it loose."

Six weeks removed from losing Bridgewater for the season, and four weeks removed from losing Peterson, perhaps for the season, the trade for Bradford is viewed within the Vikings' locker room as a message from GM Rick Spielman.

"It really showed the confidence they have in the team," Smith says. "This isn't a rebuilding year. It's not, 'Oh, we were going to be really good, but now we'll just see what happens.' It reinforced to us that the time is right now."

Or, as Boone says: "Sam came wrapped in gold."

It's clear that the king of the eye roll wouldn't agree, and that the reconsideration of Sam Bradford will continue along its unemotional, monotonous path. The cosmic importance of football eludes him. He doesn't take himself too seriously, and he sincerely hopes nobody else does either. He's been down that road before. He doesn't particularly like the view.