2021 college football story lines to watch include bevy of new QBs, Alabama's rebuild and 'Super Seniors'

This story is part of USA TODAY Sports' 25 days to college football countdown.

Full stadiums. Full schedules. One year after battling through the coronavirus pandemic, college football is set to return to normal, to the widespread happiness of coaches, players and fans across the Football Bowl Subdivision.

A few things haven't changed. The favorites for the College Football Playoff remain the same, led by Alabama, Clemson, Ohio State, Georgia, Oklahoma and a select handful of others.

The top scoring teams will be the most successful teams in the country as the FBS embraces a full-on shift toward offensive explosiveness over the antiquated notions of run-first schemes and stingy defenses.

The Big Ten and SEC will be the nation's top conferences. The Pac-12 will struggle for national recognition.

But change is afoot. There's a new playoff format under debate. Several new quarterbacks are set to ascend into stardom. There are quirky roster sizes due to seniors opting to return for a sixth season of eligibility. Those story lines and others will define the 2021 season.

New faces at quarterback

Trevor Lawrence is gone. So is Mac Jones. And Justin Fields, Zach Wilson, Kyle Trask, Ian Book and more. The loss of star power at the sport's premier position is profound. But there are more than a few rising sophomores and juniors set to claim a position among the faces of college football in 2021 and be next in line for a lucrative landing spot in the NFL draft.

Start with Lawrence's replacement at Clemson, second-year player DJ Uiagalelei, who stood in for two starts last season and flourished. (His one start at Notre Dame was remarkable even in the Tigers' defeat.) Jones will be replaced at Alabama by Bryce Young. Third-year Southern California starter Kedon Slovis is a top Heisman Trophy contender. North Carolina's Sam Howell is a rising superstar.

The best of the bunch may be Oklahoma's Spencer Rattler, who overcame a shaky start to the 2020 season and was playing as well as any quarterback in the country during the home stretch.

There also are a few starters to watch in the Group of Five ranks. Begin with Cincinnati's Desmond Ridder, the top Heisman option from the non-major conferences. Central Florida's Dillon Gabriel has thrown for 61 scores in his first two seasons. Nevada's Carson Strong is set to become a household name. Liberty's Malik Willis has blossomed under coach Hugh Freeze and is due to become a draft favorite.

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Alabama's reload

Is it a rebuild? Yeah, right. The Crimson Tide lost a number of major players — let's start with Jones, wide receiver DeVonta Smith and running back Najee Harris — but are set to reload and make another playoff run behind Young, a former five-star recruit who had a fabulous offseason. He's the new face of an offense that does lose playmakers but will remain potent, especially if new offensive coordinator Bill O'Brien makes a seamless return to the college game.

Here's the thing about Nick Saban's program: Alabama always loses its stars, if not quite to the level of this offseason, and always is right there in December and January. There's zero reason to think this year will be any different.

The "Super Seniors"

One of the roster quirks created by the COVID-19 pandemic comes from the NCAA's decision to allow every player from the 2020 season to reclaim a lost season of eligibility. Included in that move is a one-year extension on the typical scholarship cap: Teams will be allowed to go beyond 85 scholarships to include 2020 seniors who opted to return for a sixth season. (These players are referred to as "super seniors.")

While that will create roster complications across the next few years, there is an immediate benefit for senior-heavy teams suddenly teeming with depth and experience. Among those Power Five teams leaning heavily on these super seniors are Rutgers, Arizona State, Missouri and Illinois.

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Cincinnati makes another playoff run

The Bearcats are viewed as the class of the Group of Five after finishing eighth in the final playoff rankings of 2020, the best finish for a team in a non-major conference in the history of the postseason format. With Ridder and others back in the fold, the Bearcats' expectations will be to win the American and put together a case the selection committee can't ignore. In terms of making a case for the top four, these two games will tell the story: at Indiana on Sept. 18 and at Notre Dame on Oct. 2.

Big Ten coaches on the hot seat

Any breakup between Michigan and Jim Harbaugh would be phrased more as a mutual "parting of ways" than an outright dismissal. The scenario nonetheless exists that Harbaugh's 2021 season would be his last at his alma mater, especially given the nature of the four-year contract extension signed in January that was nothing more than window dressing: Harbaugh is signed through 2025 but at a reduced base salary that ranks in the bottom half of the Big Ten.

That's what happens when you go 11-8 over a two-year span, even to a coach with Harbaugh's reputation and connection to the university. It's remarkable to consider how a tenure that began with such enormous expectations — and validated that hype with three 10-win seasons, including a playoff near-miss in 2016 — could end with such a whimper.

Another Big Ten coach with worrisome job security, Nebraska's Scott Frost, is back under the microscope after the Cornhuskers' season-opening 30-22 loss to Illinois as a touchdown favorite. On display were the hallmarks of Frost-era Nebraska, including a number of self-inflicted errors that allowed new Illinois coach Bret Bielema to notch a win in his first game back in the conference.

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Oklahoma's defense

It was one of the overlooked breakthroughs from the 2020 season: Oklahoma's often-maligned defense matured under coordinator Alex Grinch to become one of the top units in the Big 12. Considering the health of the Sooners' offense and coach Lincoln Riley's track record, a similar defensive performance in 2021 would make OU not just the team to beat in the conference but one of the top teams in the entire FBS. Just think: OU's missing piece even during its several playoff runs was a stout defense. The Sooners may have the recipe for a national championship.

Oregon carrying the Pac-12

The Ducks are the team to beat in the Pac-12, with a veteran quarterback in Anthony Brown leading the offense and one of the nation's top overall players in lineman Kayvon Thibodeaux pacing a potentially potent defense. There is a case to be made for USC being just behind Oregon in the conference pecking order, though the national chatter around the Trojans remains focused more on coach Clay Helton's job security than his team's playoff chances.

After putting a team into the playoff in two of the first three years — Oregon in 2014 and Washington in 2016 — the Pac-12 has been in an extended dry spell, with each passing miss raising the temperature on the conference and the league's perceived powers. Can the Ducks break the code? After knocking on the door in 2019 under coach Mario Cristobal, anything less than being a season-long playoff factor would be viewed as a disappointment.

The future of the playoff

The proposed 12-team playoff format wouldn't become official until September at the earliest, playoff executive director Bill Hancock said in June, but the conversation that had largely defined the summer took an unexpected turn with OU and Texas announcing their intent to leave the Big 12 and join the SEC by 2025. A format that had seemingly been embraced by every Power Five conference suddenly has a far more uncertain future.

If the five major conferences do come back into agreement on the proposed format, the path to the national championship could shift to a field of 12 teams, with the top four conference champions earning a first-round bye before shifting to quarterfinals, semifinals and the finals. Would the proposed changes lead to more or less grumbling about the current format? (Don't look for less grumbling about anything.)

Follow colleges reporter Paul Myerberg on Twitter @PaulMyerberg

This article originally appeared on USA TODAY: College football: Eight story lines to watch in 2021 season