Nothing about Tanner Mangum’s trajectory as a BYU quarterback has followed a standard career arc. From the spectacular start of freshman season to a four-way fight for the starting job as a senior, he figures his college football experience qualifies as “a little bit unpredictable.”

Yeah, you could say that.

Mangum’s location varies only slightly every June, during the BYU Football Media Day in the school’s modern Broadcast Building. He sat in a corner of the room in 2016, as a returning starter who would lose his job to senior Taysom Hill. Then came a middle table assignment in 2017, as a presumed starter whose would struggle all season. And another prime spot Friday, as the only QB designated for breakout interviews.

His story keeps changing, that’s for sure. “It’s been a wild ride,” he said.

So now comes the season he labels “my last chance.” This is his opportunity to get the ending right, after a weird career that began wonderfully with winning touchdown passes against Nebraska and Boise State in his first two appearances.

Nobody would have pictured him being merely 11-10 as a starting quarterback at this point, after he went 8-4 as a freshman and seemingly was entrenched as a 50-plus-game starter — assuming he didn’t leave early for the NFL, as last summer’s Media Day line of questioning suggested. Here he is, barely more than seven months removed from an Achilles injury that ended his phase of BYU’s disastrous 4-9 season, having recovered much sooner than anticipated but facing complete uncertainty about how his BYU career will conclude.

(Chris Detrick | The Salt Lake Tribune) Brigham Young Cougars quarterback Tanner Mangum (12) throws the ball during the game at LaVell Edwards Stadium Saturday, October 28, 2017.

In August, he’ll be immersed in a QB derby that’s unlike any competition in BYU history, or maybe all of college football.

Four QBs, with three having started multiple games last season, are genuinely in the mix: freshman Zach Wilson, sophomore Joe Critchlow, junior Beau Hoge and Mangum. “We’re all aware that it could be anyone’s job,” Mangum said.

And that means delivering from the start of preseason practice, with quarterbacks coach Aaron Roderick hoping to determine the top two candidates after seven to 10 days. Judging by spring drills, with Mangum not fully participating, it would be surprising if Wilson is not one of those two. Mangum’s talent and experience are mixed by the scars of last season, when BYU went 2-6 in the games he started and the offense produced historically low numbers, resulting in a major shakeup of the coaching staff.

Jeff Grimes stood on the opposing sideline in September when Mangum’s offense couldn’t cross the 50-yard line against LSU. As the Tigers’ offensive line coach, he was conscious only of BYU’s defense that night in New Orleans. So in December, when he looked into becoming BYU’s offensive coordinator, he sought opinions from inside and outside of the Cougar program about the quality of quarterbacking.

Well, he took the job (and hastily recruited Wilson), so that tells you something. Six months later, he said, “I have absolute confidence now that we’ll have a guy, if not two or three, that we can win with.”

(Francisco Kjolseth | The Salt Lake Tribune) Quarterback Tanner Mangum is interviewed by the media as BYU hosts their eighth-annual football media day at the BYU-Broadcasting Building on Friday, June 22, 2018.

Is Mangum that guy? He hopes so, having lived through a sophomore year of backing up Hill and a junior season of directing an unproductive offense and having two significant injuries, including one that ended his season Nov. 4 in a loss at Fresno State.

Mangum later asked himself two questions: “What am I going to do next?” And “Are you going to keep the same level of enthusiasm that you did before?”

The answers: Keep working … and apparently so.

“He’s been through a lot,” fullback Brayden El-Bakri said. “He’s always positive. I just love that about him.”

More challenges await Mangum, from within the quarterback meeting room and, if he wins the starting job, from some tough opponents. BYU’s home opener is Sept. 8, his 25th birthday. The visiting California Bears may determine if that’s a memorable occasion for Mangum. So, in their own ways, might Wilson, Critchlow and Hoge.