What's more unbelievable than Nick Foles vs. Case Keenum in the NFC title game?

The phone call that altered Nick Foles' career and set into motion the quarterback carousel that improbably led to Foles vs. Case Keenum in the NFC championship game came on March 10, 2015. Chip Kelly informed Foles about a trade to the St. Louis Rams for Sam Bradford, blindsiding Foles and ending his first stint in Philadelphia about 999 years short of the "next thousand years" quip Kelly offered about Foles' future in December 2013.

Foles went from potential franchise quarterback in Philadelphia to a journeyman, with his starting stint in St. Louis short-lived – he lost his job to Keenum – before accepting life as a backup. Foles' fondness for Philadelphia eventually brought him back to where he started his career, although it took a serendipitous series of events to turn Sunday's game between the Eagles and Minnesota Vikings into the Backup Bowl.

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Just consider: Foles was traded for Bradford before losing his job to Keenum. The Eagles drafted Carson Wentz and traded Bradford to Minnesota. Keenum signed with the Vikings and replaced an injured Bradford. Foles returned to Philadelphia and replaced an injured Wentz. Now, it's Foles vs. Keenum.

"It's pretty wild, absolutely," Foles said. "I think the big message there is no matter what happens, you've just got to keep believing in yourself, keep working hard and just never give up."

Eagles coach Doug Pederson believed back in June that the Eagles could become Super Bowl contenders this season, suggesting that they had talent comparable to that of his Green Bay Packers teams that played in the NFL's final game in the 1990s. The Packers had Hall of Famer Brett Favre at quarterback and Pederson was the little-used backup.

Even the most optimistic Eagles fans likely wouldn't have figured they'd be hosting an NFC championship game without their franchise quarterback. Yet even the most pessimistic Eagles fans likely would have taken one home game against a Keenum-led team with a Super Bowl invitation on the line. And no realistic fan would have expected Foles vs. Keenum this weekend.

"I know this is what all you guys predicted back in the day, was a Foles vs. Keenum NFC championship," Keenum told reporters this week. "So good job to all you guys who predicted that."

At this time last year, the four quarterbacks remaining in the playoffs were Tom Brady, Ben Roethlisberger, Aaron Rodgers, and Matt Ryan. All four could be described as franchise quarterbacks. This year, Brady is the only one of the final quartet that fits that description.

Foles and Keenum opened the season as backups; Jacksonville's Blake Bortles was in a quarterback competition. For all the rhetoric about the importance of quarterbacks, three of the last four teams remaining start quarterbacks who aren't even locked in as 2018 starters for their teams.

"The cliche that defense wins championships is alive and well," safety Malcolm Jenkins said. "The biggest thing at the quarterback position, if you have a strong defense, is to take care of the football. All of those quarterbacks do that. They take care of the football. They don't make a ton of mistakes. So they allow their team to play patient games, to run the ball, play defense, and then strike when you have the opportunity. And in that way I think we're very similar to the Vikings in that regard."

To Jenkins' point, the Eagles, Vikings, and Jaguars were three of the top four defenses in the NFL this season and also three of the top seven rushing offenses. The Eagles had Wentz for most of the year, so they're different from Minnesota and Jacksonville in how long they have relied on an unheralded quarterback. But Foles helped the Eagles clinch a playoff spot, a first-round bye, and home-field advantage after replacing Wentz and then did what was necessary last week to advance to the conference championship game. He has thrown an interception on only 1.5 percent of his passes this season, including the playoffs.

That percentage is identical to Keenum's, who has started all but one game since Bradford reinjured his knee in Week 1. Keenum has been more prolific this season than quarterbacks saddled with the dreaded "game manager" label, but there's nothing wrong with that distinction when a defense plays as well as the Vikings' does – or in Foles' case, as well as the Eagles defense has in recent weeks.

"In both quarterbacks' cases, there's been a lot of talk about both these guys the whole season, and in our case, the last month," Pederson said." They just seem to keep sort of defying the odds and stepping up to the challenges each week. That's what's exciting and fun to see about these two guys is they've just overcome everything and have really, really helped their teams get to this position, and that's what you want."

In what could be a defensive duel on Sunday, a quarterback's mistakes might tilt a game as much as a quarterback's brilliance. Vikings defensive end Everson Griffen, who Pederson acknowledged could be a "game-wrecker," said the Vikings must stop the Eagles' run and "make Nick Foles win the game."

That's been a common objective of opponents, and the Eagles' play-calling last week suggested they didn't want Foles to lose the game. They relied on short, quick passes. Foles completed 76.7 percent of his attempts, but his completions averaged only 3.65 yards in the air. The Eagles averaged 7.04 yards after the catch, which was an effective strategy. It helped them go on extended drives, although that might be harder to do against the Vikings. Offensive coordinator Frank Reich said the Eagles need more "chunk plays." Foles said the Falcons defensders focused on keeping passes in front of them, but the game plan will likely be different against Minnesota.

"We are going to have to be able to take some shots," Foles said. "They are not going to give us as much underneath, so yeah, we are absolutely going to have to make some larger completions."

Keenum, who had a 98.3 quarterback rating this season, also relied on high-percentage throws with his wide receivers, thriving on yards after the catch. He completed 67.6 percent of his passes, which ranked second only to Drew Brees. The Vikings don't run the ball as well as the Eagles, and with the Eagles boasting the top-ranked rush defense in the NFL, Keenum must make plays to beat the Eagles.

In January, the last teams standing usually rely on their quarterbacks. Foles and Keenum couldn't secure starting jobs a few months ago, yet one of them will start in the Super Bowl in two weeks without yet securing that franchise-quarterback designation.

"I've said this a lot of times and I'll say it again: It's not about one guy," Pederson said. "Even Tom Brady has weapons on offense and playing good defense, and it's the same way with the other three teams. They have got weapons around the quarterback. They all play great defense. And … ultimately, bottom line, it comes down to who can take care of the football."

There was a time when Philadelphia wondered whether Foles could lead them to the Super Bowl. Who can forget the summer of Super Bowl expectations with Bradford? Then, earlier this year, Eagles fans prepared to invade the Twin Cities in February with Wentz jerseys.

On Sunday, Bradford and Wentz will both be on the sidelines. Foles will be on the field. It's something he could never have imagined when Kelly called nearly three years ago.

"At that moment, when I was traded, to visualize this moment and be back and just to be in Philadelphia, no," Foles said. "I had such strong ties here, I loved the city of Philadelphia, I loved being a Philadelphia Eagle. That was a tough moment for me, but I've grown so much since that moment. And to be here is surreal."

That's surreal within itself, but it's even more mind-boggling to consider all the other quarterback connections between the two teams. Foles and Keenum became close friends in 2015, when they played together on the Rams. Bradford became expendable in Philadelphia because they drafted Wentz, but the Eagles  had a buyer for Bradford only  because of Teddy Bridgewater's  August 2016 injury. It took in-season injuries to both Wentz and Bradford for Foles and Keenum to become starters again. The entire flow chart reads like a riddle.

Foles has been traded and released, demoted and promoted. He contemplated retirement and returned to his NFL roots. Somehow, he's one game away from starting in the Super Bowl.

"Life is crazy, this game is crazy," Foles said. "All the parallels that are going on and we're all seeing just shows why everyone loves this game. It's not just the playing, but all the moving pieces and everything. It's been pretty wild to look at it that way."