A word of warning: This marks the third year running that the reigning national champion has stood atop these preseason rankings. Those teams – Alabama in 2013 and Florida State last year – looked great on paper. Neither repeated as champs. This is college football. Stuff happens. It could even happen to …

1. OHIO STATE

Last season: 14-1, won Big Ten title, won College Football Playoff.

Data: ninth in total offense, 19th in total defense; 2015 signing class ranked No. 7 by Rivals.

Schedule: The Buckeyes don't play Wisconsin or Nebraska, the best teams in the Big Ten West. They'll face Michigan State in Columbus.

Why so high? Talent. Coaching. Momentum. What else do you need? Ohio State is so deep at quarterback that the Big Ten's 2013 player of the year (Braxton Miller) has been moved to receiver and the breakout star of last year's championship run (Cardale Jones) will probably be the change-of-pace guy behind J.T. Barrett. Ezekiel Elliott is probably the nation's second-best back. Urban Meyer is the nation's best coach.

What could go wrong? As shrewd as Meyer is, no coach has ever had to juggle this many quarterbacks of such high profile.

2. TCU

Last season: 12-1, tied for Big 12 title, beat Ole Miss in Chick-fil-A Peach Bowl.

Data: Tied for seventh in total offense, 19th in total defense; 2015 signing class ranked No. 34 by Rivals.

Schedule: TCU will face Baylor in Fort Worth the day after Thanksgiving. The Bears won 61-58 in Waco last year.

Why so high? The Horned Frogs were the best team omitted from the inaugural playoff. They won their final three games by the aggregate score of 145-16, and their 42-3 destruction of No. 9 Ole Miss in the Georgia Dome was a powerful closing argument. They'll carry the slight of being dropped from No. 3 to No. 6 in the final CFP rankings, and their offense — fueled by Trevone Boykin, the nation's best quarterback not at Ohio State — will again be mighty.

What could go wrong? Last year, TCU played four games decided by four points or fewer. It lost the one that mattered most. In a league without a championship game, one loss could again prove massive.

3. AUBURN

Last season: 8-5, tied for fourth in the SEC West, lost to Wisconsin in Outback Bowl.

Data: 16th in total offense, 64th in total defense; 2015 signing class ranked No. 7 by Rivals.

Schedule: The Tigers face road games at LSU, Arkansas and Texas A&M; they'll play Georgia and Alabama at home. The Sept. 5 opener against Louisville in the Georgia Dome can't be overlooked.

Why so high? The Tigers were 14 seconds from the 2013 BCS title despite having the nation's 84th-best defense. Last year the lack of stopping power caught up with them. Will Muschamp, dumped as Florida's head coach, has been hired as coordinator, and coach Gus Malzahn has gushed over the new man, calling him "the best defensive mind in the country." If Auburn can play even a dollop of defense, Malzahn's offense should do the rest.

What could go wrong? The Tigers are betting big on two new faces — Muschamp and quarterback Jeremy Johnson, who's highly regarded but who has started two collegiate games.

4. USC

Last season: 9-4, tied for second in Pac-12 South, beat Nebraska in Holiday Bowl.

Data: 29th in total offense, tied for 76th in total defense; 2015 signing class ranked No. 1 by Rivals.

Schedule: The Trojans will meet Arizona State, Notre Dame and Oregon on the road. They'll play Stanford, Washington, Utah, Arizona and UCLA in the Los Angeles Coliseum.

Why so high? For all the strong teams in the Pac-12, there's only one with the resources of Troy. Before the SEC started winning everything, the Trojans were one fourth-down failure from a third consecutive Associated Press national title. Steve Sarkisian might not be the next Pete Carroll, but he's a darn sight closer than Lane Kiffin was. The Trojans were 9-4 in Year 1 under Sarkisian, and two of those losses were last-second reversals.

What could go wrong? The Trojans can't claim to be the class of the Pac-12 until they retake Los Angeles. They've lost three in a row to UCLA.

5. ALABAMA

Last season: 12-2, won SEC title, lost to Ohio State in playoff semifinal.

Data: 17th in total offense, 12th in total defense; 2015 signing class ranked No. 2 by Rivals.

Schedule: The Crimson Tide will play at Georgia and at Auburn. The opener against Wisconsin in Arlington, Texas, won't be a walkover.

Why so high? Alabama has the nation's best talent. Even without Amari Cooper, T.J. Yeldon and Blake Sims, there's no reason to believe the Tide won't score in bunches. The defense had some lapses last season, but nobody plays shutdown defense anymore. Alabama's season — and the SEC title and maybe even the national championship — could again turn on the Iron Bowl, and those games are crazy.

What could go wrong? Jacob Coker couldn't beat out Sims as starting quarterback last season. And, not to put too fine a point on it, but the aura of Nick Saban as all-conquering has begun to flicker.

6. MICHIGAN STATE

Last season: 11-2, finished second in Big Ten East, beat Baylor in Cotton Bowl.

Data: 11th in total offense, eighth in total defense; 2015 signing class ranked No. 22 by Rivals.

Schedule: Glamour games come early and late. Oregon comes to East Lansing on Sept. 12. Ohio State will play host to the Spartans on Nov. 21.

Why so high? Other Big Ten schools keep making splashy hires — Meyer at Ohio State, Harbaugh at Michigan — but Michigan State has positioned itself as the conference's second-best program. Under Mark Dantonio, the Spartans have won 11 or more games in four of the past five seasons and posted bowl victories over Georgia, TCU, Stanford and Baylor. Oh, and quarterback Connor Cook is really good.

What could go wrong? Pat Narduzzi, long Dantonio's defensive coordinator, left to coach Pittsburgh. With apologies to Muschamp, Narduzzi was the best defensive coach in college football.

7. CLEMSON

Last season: 10-3, finished second in ACC Atlantic, beat Oklahoma in Russell Athletic Bowl.

Data: 58th in total offense, 1st in total defense; 2015 signing class ranked No. 4 by Rivals.

Schedule: Three high-profile opponents will enter Death Valley: Notre Dame on Oct. 10, Georgia Tech on Oct. 17 and Florida State on Nov. 7.

Why so high? No knock on Tajh Boyd, but Deshaun Watson of Gainesville has a chance to take the Tigers where they haven't been since Homer Jordan of Cedar Shoals High led Clemson to the 1981 national title. Had Watson been anointed Boyd's successor from the start — and had he stayed healthy — last season might have been much better. And for all the noise made by the offense, the Tigers' defense has become a greater force.

What could go wrong? Offensive coordinator Chad Morris left to coach SMU. Some believe that will hurt Clemson, but his offenses tended to stall under duress.

8. OREGON

Last season: 13-2, won Pac-12 title, lost to Ohio State in CFP final.

Data: 3rd in total offense, 87th in total defense; 2015 signing class ranked No. 17 by Rivals.

Schedule: The Ducks will miss UCLA and Arizona in the Pac-12 rotation, but they'll play Michigan State, Arizona State and Stanford on the road.

Why so high? Newton's Law holds that objects in motion stay in motion. Nobody moves like Oregon. The Ducks have won at least 10 games every season since 2007, a span that includes two coaching changes. The system is so recognizable that even the casual fan knows when Oregon pops on the screen, and not only because of the ever-changing Nike-furnished uniforms.

What could go wrong? Vernon Adams was seen as Marcus Mariota's replacement when he enrolled at as a graduate transfer. Except Adams needed another class to graduate from Eastern Washington.

9. BAYLOR

Last season: 11-2, tied for Big 12 title, lost to Michigan State in Cotton Bowl.

Data: first in total offense, 50th in total defense; 2015 signing class ranked No. 43 by Rivals.

Schedule: The Bears' first three games are against SMU, Lamar and Rice. Their first four Big 12 games are against Texas Tech, Kansas, West Virginia and Iowa State.

Why so high? This is a big-time offense even without quarterback Bryce Petty, gone after throwing for 8,055 yards in two seasons as a starter. Seth Russell will replace him, and he's highly regarded. We forget now, but Baylor actually finished ranked ahead of TCU by the playoff committee. If not for a weird loss at West Virginia, the Bears might have ended the regular season as the No. 1 team in the land.

What could go wrong? That soft schedule could become fool's gold. Baylor could hit November without having been tested, which isn't what any coach would want.

10. ARIZONA STATE

Last season: 10-3, tied for second in Pac-12 South, beat Duke in Sun Bowl.

Data: 34th in total offense, 81st in total defense; 2015 signing class ranked No. 20 by Rivals.

Schedule: Arizona State versus Texas A&M in Houston on Sept. 5 will be fun. The heralded Aggies quarterback Kyler Murray figures to debut against the nation's most unsung good team.

Why so high? Under Todd Graham, Arizona State is 20-7 the past two seasons. That's good anywhere, but it's noteworthy in the Pac-12 South, which might be — pause for SEC West fans to gripe — the nation's toughest division. The biggest news of the Sun Devils' offseason was the shift of D.J. Foster to receiver, and that's dealing from strength: Foster was a 1,000-yard rusher last season.

What could go wrong? ASU has faded at the end of the past two seasons. November losses to Oregon State and Arizona kept it from the Pac-12 title game last year.

11. BOISE STATE

Last season: 12-2, won Mountain West, beat Arizona in Fiesta Bowl.

Data: 14th in total offense, 48th in total defense; 2015 signing class ranked No. 64 by Rivals.

Schedule: This is essentially a one-game season. The one game is the opener against Washington, now coached by Chris Petersen, the guy who put Boise State on the map.

Why it's not in the top 10: The Broncos lost their quarterback and their best running back, but this program is that it always finds replacements. (Bryan Harsin did OK after succeeding Petersen, did he not?) If Boise State beats Washington, there'll be serious discussion about the Broncos not just gracing one of the major bowls but of running the table and maybe making the playoff.

12. FLORIDA STATE

Last season: 13-1, won ACC title, lost to Oregon in playoff semifinal.

Data: 35th in total offense, 61st in total defense; 2015 signing class ranked No. 3 by Rivals.

Schedule: The Seminoles will face two road tests — at Georgia Tech on Oct. 24 and at Clemson on Nov. 7 — and that's about it. It would be hard for them not to win at least 10 games.

Why it's not in the top 10: Florida State was a great team in 2013, ranking sixth in total offense and third in total defense. Last season saw major slippage on both fronts. The Seminoles were lucky not to lose a half-dozen times before Oregon did the deed. Jameis Winston will be missed as a talent, but the summer was full of non-Jameis distractions.

13. GEORGIA TECH

Last season: 11-3, won ACC Coastal, beat Mississippi State in Orange Bowl

Data: 19th in total offense, 79th in total defense; 2015 signing class ranked No. 39 by Rivals.

Schedule: Four games — road dates at Notre Dame and Clemson, home games with Florida State and Georgia — are marquee-worthy. But don't sleep on Duke at Duke.

Why it's not in the top 10: Except for quarterback Justin Thomas, who's excellent, the Yellow Jackets lost nearly everyone who handled the ball. We can say that coach Paul Johnson's offense is plug-and-play, but personnel matters. The defense has improved under coordinator Ted Roof, but Tech thrived off takeaways — 14th nationally in turnover margin — and those aren't a year-to-year constant.

14. NOTRE DAME

Last season: 8-5, beat LSU in Music City Bowl.

Data: 32nd in total offense, 71st in total defense; 2015 signing class ranked No. 11 by Rivals.

Schedule: Notre Dame plays six games against teams from the ACC. Four should be wins. Clemson at Clemson will be tough. Georgia Tech in South Bend won't be easy.

Why it's not in the top 10: The Fighting Irish collapsed at the end of the regular season, losing five of its final six games. The bowl victory over LSU served as a rallying cry. Quarterback Everett Golson, who made 22 turnovers, transferred to Florida State, leaving the job to Malik Zaire. At issue now is the defense, which is overseen by the wayfaring Brian VanGorder and was terrible last season.

15. GEORGIA

Last season: 10-3, finished second in SEC East, beat Louisville in Belk Bowl.

Data: 28th in total offense, 17th in total defense; 2015 signing class ranked No. 6 by Rivals.

Schedule: The three-game October run — Alabama and Missouri in Athens, with Tennessee at Neyland Stadium in between — should tell the tale of the Bulldogs' season.

Why it's not in the top 10: Georgia should have won the SEC East each of the past two seasons. It's the runaway choice to win the division this time, but there's uncertainty at quarterback and along the defensive front. There's also the growing feeling that this, until proven otherwise, has become a hugely talented team that loses vital games for no reason.

16. WISCONSIN

Last season: 11-3, won Big Ten West, beat Auburn in Outback Bowl.

Data: 21st in total offense, eighth in total defense; 2015 signing class ranked No. 37 by Rivals.

Schedule: The Badgers open against Alabama in Arlington, Texas. They might not play another ranked team the rest of the regular season.

Why it's not in the top 10: Wisconsin is on its third coach in four seasons. Bret Bielema and Gary Andersen left for what many perceived as lesser jobs. For a proud program that has won 10 or more games six times in the past 10 years, that's a double slap in the face. Paul Chryst was 19-19 at Pittsburgh and isn't seen as an upgrade.

17. TENNESSEE

Last season: 7-6, tied for fourth in SEC East, beat North Carolina in TaxSlayer Bowl.

Data: 90th in total offense, 36th in total defense; 2015 signing class ranked No. 5 by Rivals.

Schedule: Not quite as hard as last season's. The Volunteers will play Oklahoma, Arkansas and Georgia in Knoxville; they'll face Alabama and Missouri on the road.

Why it's not in the top 10: Tennessee appears to be the one fast-rising team in the SEC East, a division that has been won by Missouri two years running. In Butch Jones' two seasons, the Vols have scared some decent opponents without actually beating one. If this is to be a breakout season, that must change. The schedule won't make breaking out easy.

18. UCLA

Last season: 10-3, tied for second in Pac-12 South, beat Kansas State in Alamo Bowl.

Data: 22nd in total offense, 63rd in total defense; 2015 signing class ranked No. 13 by Rivals.

Schedule: Games 4-6 bring Arizona, Arizona State and Stanford as opponents, the first and last on the road. The Bruins do avoid Oregon this regular season.

Why it's not in the top 10: UCLA was ranked No. 9 and positioned to clinch the Pac-12 South on Nov. 28. It lost 31-10 at home to Stanford, dashing the Bruins' hopes for both a conference title and a playoff berth. With USC on the rise and the South getting tougher every year, that might have been their best shot for a while.

19. ARKANSAS

Last season: 7-6, last in SEC West, beat Texas in Texas Bowl.

Data: 60th in total offense, 10th in total defense; 2015 signing class ranked No. 25 by Rivals.

Schedule: Over the regular season's final nine weeks, the Razorbacks will play Texas A&M, Tennessee, Alabama, Auburn, Ole Miss, LSU, Mississippi State and Missouri.

Why it's not in the top 10: Arkansas got great mileage from its last-place finish, shutting out two ranked teams and scaring four others. The Hogs' old-school approach — they play as if Bielema were still coaching Wisconsin — is out of step with the newfangled hurry-up stuff, and sometimes they get outrun. But they never get outfought.

20. MISSOURI

Last season: 11-3, won SEC East, beat Minnesota in Citrus Bowl.

Data: 95th in total offense, 23rd in total defense; 2015 signing class ranked No. 27 by Rivals.

Schedule: Mizzou should be favored in nine of its first 10 games, the exception being its Oct. 17 date in Athens. It closes with Tennessee and Arkansas, though.

Why it's not in the top 10: The Tigers arrived from the Big 12 as a ride-along with Texas A&M and have won consecutive East titles. Last year they had an awful offense and went 7-1 in league play. How did they do it? Through coaching — Gary Pinkel is excellent — and player development. But it can't happen three times in a row, can it?

21. ARIZONA

Last season: 10-4, won Pac-12 South, lost to Boise State in Fiesta Bowl.

Data: 25th in total offense, 103rd in total defense; 2015 signing class ranked No. 41 by Rivals.

Schedule: There's no easy path in the Pac-12 South. The Wildcats face road games at USC, Stanford and Arizona State.

Why it's not in the top 10: Arizona stole the South, but almost wished it hadn't. It lost 51-13 to Oregon in the conference title game and was upset in the Fiesta. Even with linebacker Scooby Wright wreaking havoc, the defense was wretched. Quarterback Anu Solomon is skilled enough to allow Rich Rodriguez's offense to win some shootouts.

22. OKLAHOMA

Last season: 8-5, tied for fourth in Big 12, lost to Clemson in Russell Athletic Bowl.

Data: 23rd in total offense, 51st in total defense; 2015 signing class ranked No. 14 by Rivals.

Schedule: The Sooners will face Tennessee in Knoxville on Sept. 12. In November, they'll play TCU in Norman and Baylor in Waco — on consecutive Saturdays.

Why it's not in the top 10: Oklahoma lost five games last season despite the presence of Travis Knight, a quarterback who'd been MVP of a Sugar Bowl victory over Alabama, and running back Samaje Perine, who gained an NCAA-record 427 yards against Kansas. The question is whether that was a one-year blip or the start of a real decline.

23. LSU

Last season: 8-5, tied for fourth in SEC West, lost Music City Bowl to Notre Dame.

Data: 77th in total offense, ninth in total defense; 2015 signing class ranked No. 8 by Rivals.

Schedule: The Tigers play South Carolina and Florida from the SEC East, neither of which is expected to be anything special. They'll face Auburn in Baton Rouge, Alabama in Tuscaloosa.

Why it's not the top 10: The one constant in the LSU program — beyond Les Miles doing strange things — was defensive coordinator John Chavis. He left for Texas A&M, weary of having to prop up a pedestrian offense. This remains a very talented team, but Kevin Steele, the new defensive coordinator, isn't nearly as accomplished as Chavis.

24. STANFORD

Last season: 8-5, second in Pac-12 North, beat Maryland in Foster Farms Bowl.

Data: 75th in total offense, third in total defense; 2015 signing class ranked No. 18 by Rivals.

Schedule: The Cardinal face USC, UCLA and Arizona from the Pac-12 South and finish against Notre Dame. Oregon does come to Palo Alto this year.

Why it's not in the top 10: Stanford played six ranked teams last season, losing to five mostly because it couldn't score. In each of the five losses, it failed to muster even 20 points. Eight starting defenders are gone, but the Cardinal have been playing rugged defense since Jim Harbaugh was coaching and won't stop now.

25. TEXAS A&M

Last season: 8-5, sixth in SEC West, beat West Virginia in Liberty Bowl.

Data: 30th in total offense, 102nd in total defense; 2015 signing class ranked No. 10 by Rivals.

Schedule: The Aggies open against Arizona State in Houston. They get a break in that both Alabama and Auburn come to College Station. They play Vanderbilt on the road, another break.

Why it's not in the top 10: A&M was ranked No. 6 in the nation in October and freshman quarterback Kenny Hill was a Heisman candidate. Hill was suspended later in the season — he transferred to TCU — and the defense stopped nobody and everything fell apart. With Chavis running the defense and Kyler Murray playing quarterback, that should change.