The Alabama Crimson Tide are the favorite to win college football's next national championship, but needing to replace the entire starting secondary could be the flaw that keeps them from even reaching the College Football Playoff.

We're not just picking on Alabama, though. All of the teams with legitimate aspirations of being chosen by the CFP selection committee have major red flags that could turn a dream season into a nightmare.

Both Georgia and Auburn have question marks in the running game. Michigan and Washington are lacking in proven receiving threats. And let's just say Alabama isn't the only team with concerns on defense.

These issues won't bury all of these teams. Somehow, some way, four teams are going to the College Football Playoff. But these are the hurdles the top contenders will need to clear in order to get there.

Teams are listed in ascending order of likelihood of winning the national championship, per the consensus title odds on OddsShark as of July 2.

10. Washington Huskies

Championship Odds: 29.4-1

Biggest Flaw: Lack of big-play receiver

There's a lot to like about this Washington team. Jake Browning and Myles Gaskin are both back for the rarely seen combo of four-year starters at quarterback and running back. The Huskies also bring back several key linebackers and what might be the best secondary in the entire country.

If they don't figure something out at wide receiver, though, they're going to have a hard time winning the Pac-12—let alone a national championship.

In recent years, Washington had remarkable playmaking receivers in John Ross and Dante Pettis. But Ross went pro after the 2016 campaign, and Pettis became a second-round draft pick this past April, leaving what, exactly? The only returning player who had multiple receiving touchdowns in 2017 was Gaskin, and Pettis was the only Husky who averaged better than two receptions per team game.

If he's healthy after missing most of last year with a broken ankle, Chico McClatcher would appear to be the top candidate to emerge as a go-to receiver. He made 31 receptions for 574 yards and five touchdowns as a sophomore in 2016. But how much of that was potential to become a No. 1 target and how much of it was simply McClatcher getting open because opponents were more concerned with Ross and Pettis?

Considering tight end Hunter Bryant (22 receptions, 331 yards, 1 TD) is the top returning receiver, though, there aren't many other options to nominate.

9. Auburn Tigers

Championship Odds: 23.6-1

Biggest Flaw: Inexperience at running back and offensive line

Since Gus Malzahn took over as head coach before the 2013 season, Auburn has always run the ball well. The Tigers led the nation in rushing yards per game in his first year at the helm, and they have averaged 5.3 yards per carry and 254.5 yards per game over the course of his five seasons.

Maintaining that ground dominance after losing both star running backs and most of the offensive line will be a major challenge.

On the OL side of the equation, the Tigers lost starters Braden Smith, Austin Golson, Casey Dunn and Darius James as graduates. Only Smith was deemed good enough to get drafted, but replacing all four of those guys in one cycle won't be easy. If redshirt freshman and 2017 5-star OT Calvin Ashley is not yet ready for a starting gig, it'll be even worse.

As far as the ball-carriers go, Kerryon Johnson (285 attempts, 1,391 yards, 18 TDs) was a strong Heisman candidate prior to the shoulder injury that limited him in his final three games. And though Kamryn Pettway wasn't all that great this past season, the former fullback had an incredible stretch in the middle of the 2016 season. Losing both of those backs as early entrants to the NFL draft was a huge blow to Auburn's run game.

The Tigers do still have standout QB Jarrett Stidham as well as all four of his favorite targets from last season. They could thrive with a more pass-heavy approach to the offense. But given the roster transformation, there's a good chance Auburn will fail to reach its potential if it insists on continuing to run the ball close to 50 times per game.

8. Wisconsin Badgers

Championship Odds: 23-1

Biggest Flaw: Too many holes to fill in secondary

Wisconsin led the nation in passes defended last season. According to CFBstats.com, the Badgers had 20 interceptions and 75 passes broken up. Part of that is because they played such a weak schedule and seemed to always have the luxury of holding a lead against an inferior opponent, but the bigger factor was talented veterans in the secondary.

What will the Badgers do now that the bulk of that unit is gone?

CB Nick Nelson (21), S Natrell Jamerson (12) and CB Derrick Tindal (12) combined for 45 of those pass breakups, and all three of those starters are now out of the picture. Wisconsin also lost S Joe Ferguson, who tied linebacker T.J. Edwards (at least he'll be back) for the team lead with four interceptions.

Basically, the Badgers are getting starting safety D'Cota Dixon back, and that's about it—and even that fifth-year senior is recovering from offseason shoulder surgery.

To be fair, if there's one program in the country that has shown the propensity to turn walk-ons into borderline All-Americans, it's Wisconsin. Paul Chryst seems to find diamonds in the rough year after year. So perhaps a guy like Madison Cone or Eric Burrell suddenly breaks out as a sophomore after barely seeing the field as a freshman. Until then, though, lack of experience in the secondary is a glaring concern for Wisconsin.

7. Oklahoma Sooners

Championship Odds: 22.6-1

Biggest Flaw: Rush defense

Oklahoma's rush defense was already considerably less than stellar. As the only team in the Big 12 that ranked in the top 30 nationally in rushing yards per game—and with an offense so potent that opponents often abandoned the run by halftime—the Sooners were able to withstand this weakness during the regular season.

In the College Football Playoff, however, Georgia repeatedly exposed Oklahoma's inability to stop the run.

And that was before the Sooners lost leading tacklers Emmanuel Beal and Ogbonnia Okoronkwo, as well as defensive end D.J. Ward. With that trio out of the picture, things could get ugly.

One potential saving grace to keep an eye on is Levi Draper. He was one of the top gets in Oklahoma's 2017 recruiting class, but he missed the entire season due to a shoulder injury. In what is already a young and inexperienced projected starting front seven, Draper could quickly develop into a key cog.

But even though redshirt freshmen often do make a big positive impact, you know things aren't ideal when you're hanging your hopes on someone who has never played on a collegiate level.

6. Penn State Nittany Lions

Championship Odds: 18.8-1

Biggest Flaw: Wholesale changes on defense

Penn State endured two colossal departures from last year's CFP contender: Do-it-all running back Saquon Barkley became the No. 2 pick in the 2018 NFL draft, and offensive coordinator Joe Moorhead was hired as the head coach at Mississippi State.

However, neither of those moves is the primary reason to worry about the Nittany Lions' chances of winning it all. They still have an impeccable running back in Miles Sanders, and by promoting from within (Ricky Rahne), there's no good reason to expect a major philosophical shift at OC.

Rather, the cause for concern is the near-total overhaul in defensive personnel. Penn State lost eight of its primary starters on defense—including the entire secondary—leaving LB Koa Farmer and DE Shareef Miller as the pillars around which the rebuilding will occur.

The Nittany Lions do get John Reid back after a torn ACL cost him the entire 2017 season. They also have sophomore DB Lamont Wade and freshman DE/LB Micah Parsons in the "highly touted recruits who could become All-Americans" department.

In other words, the cupboards aren't completely bare. Penn State wouldn't have the sixth-best odds to win it all if the situation was that dire. But somewhat of a step backward on defense is to be expected, which would make the loss of Barkley that much tougher to overcome.

5. Michigan Wolverines

Championship Odds: 14.2-1

Biggest Flaw: Lack of proven receivers (and a brutal schedule)

For the second straight year, the biggest question facing Michigan football is: Who's catching the passes?

The Wolverines lost all three of their leading receivers from the 2016 roster, so they entered this past season with a mixed bag of inexperience, freshmen and members of the backfield who occasionally made receptions in the flats. Thanks in part to a revolving door at quarterback, things went about as poorly as expected. No Michigan player finished 2017 with more than 31 receptions, 307 yards or three touchdowns.

On the bright side, each of the nine Wolverines who made at least six catches is back for another season. On the even brighter side, Ole Miss transfer—and 2016 No. 4 overall recruit—Shea Patterson has been ruled immediately eligible to play and is expected to be the starter.

If the recruiting stars align, he and 2017 No. 1 WR Donovan Peoples-Jones could be the heavenly match that puts Michigan's offense back on the map after a woeful 2017 campaign. But if DPJ has another disappointing season (22 receptions, 277 yards, 0 TDs as a freshman), is there anyone else who will emerge to become Patterson's big-play target?

Even if the Wolverines get that straightened out, though, the schedule from hell could be their undoing. They open the season with a road game against Notre Dame, which will immediately put the new quarterback to the test. Later on, they have three consecutive games against Wisconsin, (at) Michigan State and Penn State. And then they close out the regular season at Ohio State.

In terms of talent on the roster, Michigan deserves to be a top-five team. However, getting through that gauntlet with zero or one losses would be quite the feat.

4. Georgia Bulldogs

Championship Odds: 7.66-1

Biggest Flaw: Lost anchors at running back

Let's be sure to state up front that Georgia has a bunch of great running back options on its roster. D'Andre Swift was a 5-star talent who averaged 7.6 yards per carry as a true freshman last year. Kirby Smart signed two more incredible backs in this year's class in the forms of Zamir White and James Cook. Both Brian Herrien and Elijah Holyfield have proved themselves to be valuable reserves. And Mecole Hardman Jr. is one heck of a gifted "In Case of Emergency" option.

However, Nick Chubb and Sony Michel combined for 2,572 rushing yards and 31 touchdowns last season as seniors. Those go-to guys will not be easy to replace, no matter how many recruiting stars the Bulldogs have at their disposal.

Chubb and Michel were the foundation upon which Georgia's run to the national championship game was built. They gave Georgia one of the most unstoppable rushing attacks in the nation, and they made it possible for Jake Fromm to keep his head above water as a true freshman quarterback.

Can Swift and Co. fill that two-headed void?

It's possible. It might even be probable. It's far from guaranteed. And given how great the defensive lines at Clemson, Ohio State and Alabama figure to be, this is not a great year to try to win a title with anything less than a dominant run game.

3. Ohio State Buckeyes

Championship Odds: 6.5-1

Biggest Flaw: Inexperience at quarterback

For the first time in what feels like at least a decade, J.T. Barrett isn't walking through that tunnel of the Horseshoe. Instead, the Buckeyes are handing the reins to a redshirt sophomore who has only appeared in one meaningful game in his college career.

The good news is Dwayne Haskins was brilliant against Michigan in his relief of an injured Barrett last November, propelling the Buckeyes to a come-from-behind victory over their loathed rival. Moreover, almost all of last year's running backs and receivers are back for another year, so the new quarterback has a full cupboard with which to work.

Still, we're talking about replacing a four-year starter and team leader with someone who has faced 20 minutes of legitimate in-game pressure in the past 30 months.

He has the talent to be special, but there's no telling how well Haskins will respond to that inevitable first bit of adversity, nor how durable he's going to be over the course of three-plus months. And in a Big Ten East division that has four of the 12 favorites to win the national championship, Ohio State doesn't have any margin for error for growing pains.

2. Clemson Tigers

Championship Odds: 5.68-1

Biggest Flaw: Quarterback controversy

Plenty of title contenders have potential quarterback battles to sort out this fall. Alabama has to choose between Jalen Hurts and Tua Tagovailoa. Georgia's Jake Fromm could get challenged by incoming freshman Justin Fields. And at Oklahoma, Austin Kendall is going to give Kyler Murray a run for his money.

None of those competitions are going to affect the national landscape quite like the decision facing Dabo Swinney and Clemson.

Five years ago, this would have been a no-brainer. Kelly Bryant is the senior who just led Clemson to the national semifinals, and Trevor Lawrence is a true freshman. Conventional wisdom says: Stick with the veteran and let the young'n learn from the sideline. But given what Hurts, Fromm and Tagovailoa accomplished as true freshmen over the past two seasons—and given the fact that Lawrence has the potential to be a once-in-a-decade type of talent at quarterback—it's a tough call.

And considering how different Bryant and Lawrence are, it's not like Clemson can just bounce between the two and ride the hot hand. Bryant—like Tajh Boyd and Deshaun Watson before him—thrives with an RPO-heavy attack. Lawrence, on the other hand, is a pro-style QB with a big arm and minimal dependency on his legs. Trying to play them interchangeably would require two separate playbooks.

Perhaps the only wrong decision here is indecision. If Swinney goes all-in on either Bryant or Lawrence and gets a healthy season from the one he chooses, Clemson should win the ACC and compete for the national championship for a fourth consecutive year.

1. Alabama Crimson Tide

Championship Odds: 2.06-1

Biggest Flaw: Defensive backfield

In most preseasons, trying to find a potential flaw in Alabama is about as simple as searching for a four-leaf clover or a needle in a haystack. After so many consecutive years of Nick Saban getting just about whatever he wants in recruiting, there's so much talent on the roster that it's almost impossible to point to any position and say, "Oh yeah, that's going to be a problem."

However, this year—even though the Crimson Tide are favored to win it all—it is abundantly clear where their downfall is most likely to originate: the secondary.

This unit was anchored by Minkah Fitzpatrick, Levi Wallace, Anthony Averett, Ronnie Harrison, Hootie Jones and Tony Brown last season, but not one of those six defensive backs remains on the roster.

As a result, the Crimson Tide are effectively starting over from scratch. Former wide receiver Trevon Diggs, incoming transfer Saivion Smith and scarcely used players like Daniel Wright, Xavier McKinney and Jared Mayden are all strong candidates for starting jobs.

Fortunately, the Crimson Tide are still loaded in the front seven, which should help keep pressure off the inexperienced secondary. But Ohio State went through a similar overhaul in its defensive backfield last summer, and there's no question the Buckeyes were less equipped to defend the pass because of it.

How much of a slip Alabama suffers in that department may determine whether it plays in the national championship for a fourth consecutive year.

Kerry Miller covers college football and men's college basketball for Bleacher Report. You can follow him on Twitter, @kerrancejames.