The Big 12 is absolutely wide open

Oklahoma has sat atop the Big 12 mountain for the past three seasons, and even with Baker Mayfield leaving for the NFL, the Sooners are still the favorites to continue their reign.

However, while Oklahoma is certainly the team to beat, the Big 12's depth is its defining storyline headed into the 2018 campaign.

Baylor and Kansas appear set to prop up the other eight teams once again, but defensive juggernauts Texas, TCU, and the Will Grier-led West Virginia will be snapping at the Sooners' heels all season long.

And between those two classes of teams is an intriguing middle tier containing Oklahoma State, Iowa State, Kansas State, and Texas Tech - all of which have the talent to make some noise in what is maybe the most wide-open conference in the nation.

Here's a look at where each Big 12 team stands in the conference:

Oklahoma

The Mayfield era is over, and his shoes will be impossible to fill. But while Oklahoma's offense will surely drop from its 2017 heights, it could be just as fun thanks to the dynamic Kyler Murray.

Murray, who was selected by the Oakland Athletics with the No. 9 overall pick in the 2018 MLB Draft, will be the team's starter before heading off to fulfill his baseball dream. The former No. 1 dual-threat quarterback should bring an extra dimension to the Sooners' offense with his athleticism and top-tier scrambling ability, even if he's nowhere near the passer Mayfield was.

Oklahoma shouldn't have to rely too heavily on their QB, though, thanks to the presence of darkhorse Heisman candidate Rodney Anderson, who somehow racked up over 1,400 yards and 19 total touchdowns in 2017 despite not starting until midseason.

It'll be the defense that determines the Sooners' fate in 2018, though. It was carried by Mayfield and Co. until the playoffs last season, when Georgia dropped 54 points on them in an overtime win. It's a young unit, so there's plenty of room for growth, but Lincoln Riley will need it to happen fast if he's to make it back-to-back playoff appearances.

West Virginia

The Mountaineers should be a touchdown-scoring machine with the returning Grier under center. The quarterback was a revelation in his first year with the program following a messy transfer from Florida, tossing 34 touchdowns and nearly 3,500 yards before a broken finger prematurely ended his season.

With Mayfield gone from the Big 12, and fellow star passers like Lamar Jackson and Sam Darnold also in the NFL, Grier could be the guy in college football in 2018. He's not exactly hurting for elite weapons, either. Receivers David Sills and Gary Jennings will be his top two targets. The former tied for the most touchdown catches in the nation with 18 scores while the latter topped the conference with 97 catches.

Even a Heisman-winning campaign from Grier, though, likely won't be enough to topple the Sooners unless the defense makes an unexpected leap. West Virginia's 6.1 yards-allowed-per-play average last season was 96th in the nation, and the unit's depth is arguably even worse, with only four starters returning.

If Grier can get some more help from the defensive side of the ball, and continues his development into the best passer in college football, a first Big 12 championship may be in the cards.

TCU

While the rest of the Big 12 zigs, the defense-oriented Horned Frogs keep zagging - and to great success, as head coach Gary Patterson led his well-rounded and lightning-quick unit to a second-place finish last season.

Defensive end Ben Banogu and linebackers Ty Summers and Jawuan Johnson headline a unit that's set to continue its streak of six straight top-two finishes within the conference in yards per play allowed, but that needs to get the Oklahoma monkey off its back.

The Mayfield-led Sooners torched TCU twice in 2017, beating them by a combined 42 points. TCU has played Oklahoma close in years past, and the loss of Mayfield should make it a far more competitive matchup in 2018.

However, Riley's system is still in place, and Murray presents a new problem for TCU's talented defensive line. The pressure is on for quarterback Shawn Robinson to develop quickly and give TCU some of its own firepower after throwing just 27 passes last year.

Texas

After almost a decade of uncharacteristic irrelevance, 2018 could be the year Texas finally regains its former glory.

Head coach Tom Herman is shouldering mammoth expectations entering his second year in charge of the program. His rookie year showed promise, and the defense looked close to elite outside of an embarrassing season-opening defeat to Maryland.

But seven wins, including a victory in the Texas Bowl, just doesn't cut it for the Longhorns, even after three painful years of stagnation under Charlie Strong. The state of Texas demands a title contender, and if Herman's squad looks far from that status by the end of Year 2, his seat will get uncomfortable.

The key could be sophomore Sam Ehlinger. The passer struggled with turnovers in key moments as a true freshman, but he should be a smarter player for it. And after ranking 101st in yards per play last season, Texas' offense needs him to be if the unit is to avoid wasting the defense's efforts.

Herman and defensive coordinator Todd Orlando are arguably the best HC-DC combo in the conference. The offensive talent isn't there yet, but Texas could ride its top-tier coaching and the nation's No. 3 recruiting class back up to the top of the Big 12.

Oklahoma State

Few quarterback-receiver combinations were as exciting to watch as Mason Rudolph and James Washington over the past three years. The duo lit defenses up to the tune of nearly 1,600 yards last year (Rudolph finished with 4,904 passing yards in total), but both are now in the NFL. Head coach Mike Gundy has his work cut out to replace the two school legends.

Justice Hill should be the driving force of Oklahoma State's offense moving forward, regardless of if Gundy pegs Rudolph's 2017 backup, Taylor Cornelius, or Hawaii graduate transfer Dru Brown as the starter. The running back racked up nearly 1,500 rushing yards despite the unit running through Rudolph and Washington.

On the other side of the ball, the Cowboys' biggest concern is the losses of defensive backs Tre Flowers and Ramon Richards. Oklahoma State was already susceptible to the deep ball in 2017 - it ranked 81st in 20-plus-yard plays allowed in 2017, according to Football Outsiders - and will need to figure out that weakness before a brutal, and likely season-defining, final three games against Oklahoma, West Virginia, and TCU.

Iowa State

Head coach Matt Campbell's team is boosted by a host of returning players on both sides of the ball. Quarterback Kyle Kempt and running back David Montgomery, who cracked 1,000 yards in 2017, are the most notable names among the 13 returning starters (seven on offense, six on defense).

However, after posting its best season in terms of wins since 2000, Iowa State won't be underestimated again. Campbell will need to squeeze every ounce of talent from his roster if the program is to take another step forward and earn more shock wins.

The Cyclones were able to upset the likes of Oklahoma and Memphis thanks in part to their great run defense. But linebacker Joel Lanning and defensive end J.D. Waggoner are gone after combing for 24.5 tackles for loss and 10.5 sacks. Iowa State will need to find other playmakers in its front seven if it's to create a worthy sequel to the successful 2017 campaign.

Baylor

Head coach Matt Rhule is entering his second year at Baylor, but it should really be considered his first true season after spending 2017 cleaning up the mess left by Baylor's sexual assault scandal.

Baylor managed just one win last season - losing a handful of close games - but could force its way into the middle class of the Big 12.

The Bears return the vast majority of their production from a year ago, and sophomore quarterback Charlie Brewer appears to be the answer under center after completing more than 70 percent of his passes in his five 2017 starts as a true freshman.

Kansas State

Kansas State lost both of its coordinators this offseason, meaning head coach Bill Snyder will again have to work some magic to avoid a disappointing season.

The Wildcats had a rotating cast of quarterbacks in 2017, and while the uncertainty at the position continues, the offense should be solid thanks to an entire returning offensive line and a strong stable of backs headlined by Alex Barnes.

Snyder dealt with a cancer scare last year but willed his team to five wins in its last six games after a poor middle of the season. This schedule features four projected top-25 teams, so the Wildcats may have trouble carrying over that momentum.

Texas Tech

Kliff Kingsbury's job was likely saved by a win in the final game of the regular season, earning Texas Tech a place in the Birmingham Bowl. But the head coach's seat remains red-hot entering 2018.

Kingsbury's record sits at 30-33 after six years, and he'll likely need to top eight wins if he's to survive for an eighth. He does have nine starters returning on defense, providing the team some stability.

The offense, on the other hand, has no returning skill-position players, which should be a major concern considering it has historically been the stronger unit under the former quarterback.

Kansas

After beating Southeast Missouri State in the season opener last season, Kansas lost 11 straight games by a mind-boggling 319 points combined. The Jayhawks return most of their production from a year ago, but it's hard to view that as a positive.

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