Meet Tanner Mangum, the unlikely hero behind the BYU Hail Mary

BYU stuns Nebraska on final-play Hail Mary (0:57)

On the final play of the game, BYU's desperation pass was caught in the end zone to stun the Cornhuskers in Nebraska. (0:57)

Tanner Mangum returned to Idaho on the first Wednesday of June after spending 22 months as a missionary in the Antofagasta region of Chile.

Four days later, he left his parents' home northwest of Boise on a new mission -- to play quarterback at Brigham Young.

You may see these two journeys as unrelated, but they are inseparable to Mangum. A true freshman who turned 22 on Tuesday, Mangum will make his first start for the Cougars on Saturday at LaVell Edwards Stadium against his hometown school, Boise State, fulfilling a dream he has kept half his life.

A season-ending foot injury suffered by senior Taysom Hill pressed Mangum into unexpected action last week in the second quarter of BYU's season opener at Nebraska. He responded with a 7-for-11 passing effort in the 33-28 BYU victory and led a 76-yard drive in the final 48 seconds, capped by a 42-yard Hail Mary on fourth down.

So unlikely was his starring role that Mangum's parents skipped his first college game to watch Tanner's brother, Idaho State senior Madison Mangum, snag a highlight-reel catch in the Bengals' win over Black Hills State. (The Mangum brothers were 1-2 in the SportsCenter Top 10 on Saturday.) Michael and Karen Mangum followed the BYU comeback on their phones before losing the broadcast during the last drive. They knew the result only as text messages began to bombard their phones -- and then a call arrived from Parker, the oldest Mangum sibling and an ex-Cougar.

"He could hardly contain himself," Karen said. "It was: 'He did it! He did it! We won the game!"

Mangum attributes his poise under pressure to the life experience gained while serving his LDS church mission. It gave him the perspective, Mangum said, to execute smoothly away from home before nearly 90,000 in his college debut.

Compared to the harsh conditions of the Atacama Desert, Memorial Stadium was a breeze.

"We're going to win a lot of games with him," said receiver Mitch Mathews, who caught the game-winning pass.

Mangum's path to BYU began in earnest 10 years ago. Alongside his brother, Parker, who played receiver in Provo from 2007 to 2009, Tanner showed up at football camp when Bronco Mendenhall was promoted to head coach 2005.

"So here's all these little kids," Mendenhall said this week, "and there's one who can throw it like he has a rocket launcher. The ball just came out different. It sounded different. It spiraled different."

Mendenhall and Brandon Doman, the former BYU QB who coached at the school from 2005 to 2012, got to know Mangum. Then they got to know his family.

Mangum's father, Michael, played high school basketball in Salt Lake City. Tanner's mother, Karen, raised in Southern California, still plays competitive tennis. Both earned their undergraduate and master's degrees from BYU.

But their five children raised the bar. After Parker, Meredith Mangum played soccer at Boise State. Madison Mangum began his football career at BYU and now makes highlight-reel catches at Idaho State. Tanner is the fourth Mangum to play collegiately, and Abby, 16, stars in basketball and volleyball at Eagle (Idaho) School.

"That's not an accident," Mendenhall said. "The talent is there, but they've instilled the confidence and the work ethic."

An Eagle Scout who played the cello for five years and sang in the high school choir, Tanner started at Timberline High School and transferred to Eagle before his junior year, missing part of that season with a fractured collarbone.

His recruiting profile exploded in July 2011 at the Elite 11 finals, as he shared MVP honors with Jameis Winston. BYU wanted him, and Mangum had enjoyed a long relationship with Doman. But the college decision was difficult.

"He fell in love with Chris Petersen here at Boise State," Karen Mangum said.

Bryan Harsin, the current Boise State coach and former offensive coordinator under Petersen, developed a bond with Mangum as well. So much so that Mangum wavered often between the schools before settling on BYU.

Mangum never wavered, though, on the mission, despite the temptation to follow the path of BYU quarterback greats Steve Young, Robbie Bosco and Ty Detmer -- none of whom served as missionaries before embarking to college.

Instead, Mangum chose the route of Doman, John Beck, Max Hall and Hill. Mangum's father and two brothers also served missions.

"He felt strongly that he wanted to go," Tanner's mother said.

Mangum grayshirted at BYU in the fall of 2012, preserving a year of eligibility, and he practiced with the Cougars in the spring of 2013.

"It's a completely different story if he doesn't have that year," Mendenhall said. "My level of comfort is night and day."

Mangum left for Chile on July 31, 2013. He was allowed two calls home via Skype per year -- on Christmas and Mother's Day. He emailed his family once a week.

For the first year of his service, Mangum did not take a hot shower. He packed one football, and occasionally tossed it with BYU receiver Moroni Laulu-Pututau, who was part of the same missionary group. But those days were rare.

They assisted in earthquake and flood relief. Mangum helped paint houses and build structures. A daily focus, he said, involved "keeping your cool and doing the best you so you can help others around you."

For the final six months of his mission, Mangum served as a leader, traveling throughout the region to help educate other missionaries.

"It's just incredible what happens," Karen Mangum said. "They come back so much more focused. They're independent thinkers. They are responsible. I think it makes a big difference. They have goals. They have direction. They've learned to do hard things."

Like how to throw a game-winning Hail Mary? Not exactly, but the moment Saturday did not overwhelm Mangum.

"I was just reminding myself: We've practiced. We've worked. We're ready," Mangum said, "and reminding myself that I've got this. I just tried to stay calm, just tell myself this is fun, this is pretty cool to be out here playing."

Still, Mangum faces obstacles on the road to success in this first year back. According to Doman, missionaries need 12 months to regain muscle memory and strength. "You have to get your mental frame of mind back," said Doman, who waited 2½ years after his return to start at QB in 2000. "I still feel it's an unfortunate scenario for Tanner, but if there's any kid that I've been around who's capable of making this work, it's him. It's because of his maturity and his background with his family.

"He's got a chance."

Mangum finds himself in this spot because of BYU's recent bad luck with quarterbacks. Hill, before the latest injuries, missed chunks of his 2012 and 2014 seasons. Recent quarterback signees Billy Green and Ammon Olsen transferred.

Last spring, with Hill on the mend and sophomore McCoy Hill injured in the opening workout, BYU needed graduate Christian Stewart -- an eight-game starter last year in place of Hill -- to fill the position just so the team could practice.

So when Mangum returned in June, he stepped into the backup spot. BYU added true freshmen Beau Hoge and Koy Detmer Jr., but Mangum never relinquished the No. 2 job.

"I had a lot more concerns before Saturday," Mendenhall said. "It looked like he had been doing it for a couple seasons.

"The mental capacity and decision-making will be there. It's just, can his body keep up with it, week in and week out? That's the biggest concern with any missionary. We have a completely different protocol for those players when they come back. Unfortunately or fortunately, we've had to accelerate Tanner's faster than probably anyone."

After the visit from Boise State, BYU travels to UCLA and Michigan.

It's trial by fire for Mangum. At least he's accustomed to challenges.