Alabama-Florida State has staked its claim to the title of biggest season-opener in college football history. Michigan vs. Florida in Arlington, Texas, is Saturday's chief undercard, and it is worthy of a different label: Most mysterious opener.

In the big picture of the 2017 season, it seems somewhat easy to project what the Wolverines and Gators will be. In Year 3 under coaches Jim Harbaugh and Jim McElwain, both squads are likely top-20 teams, again, but they're unlikely to get over the hump and win conference championships. The most likely outcome is that each will win 8-10 games and attempt to set the stage for bigger things in 2018.

The matchup between the No. 11 Wolverines and No. 17 Gators is the second-most high-profile of the weekend, and no game may be more difficult to confidently predict. It makes for an intriguing afternoon featuring two teams that have had a lot of similarities in recent years, especially the angst during the offensively challenged coaching tenures of Brady Hoke and Will Muschamp. Since 2010, Michigan is 58-32 and Florida is 56-34. Both have struggled to put together complete teams -- Michigan's defense was a mess under Rich Rodriguez, but the imbalance gradually flipped -- and both are still trying to clean up previous problems and rise to the top of their conferences.

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Florida has gone to the SEC title game in back-to-back seasons and Michigan has stabilized as a national threat again, but the rebuilds are not yet complete. Saturday will be the first step in showing that these teams are capable of breaking through slightly tempered 2017 expectations.

Questions abound, however. Let's run through the 10 biggest mysteries heading into Saturday's game.

10. Michigan's roster

College football rosters are typically updated before spring practice, then updated again after freshman arrive for the preseason. It's all basic stuff, and it's never a big deal. Michigan couldn't help but make things more difficult. As of Tuesday night, the Wolverines' roster on their official website still showed the 2016 squad, and NJ.com's attempt to get a roster through a FOIA request was unsuccessful.

Early Wednesday morning, however, the "mystery" -- finding an unofficial Michigan roster was hardly difficult -- was finally solved, via a tweet:

Last year, Michigan made headlines by refusing to release a depth chart. Now, on top of that, it waited until just a few days before kickoff to release a list of players on the team, the latest attention-grabbing ploy during the Harbaugh era.

"He obviously felt that they needed to do some things to become relevant," McElwain told reporters this week. "That was his choice. It's probably not something I'd do. That's all right."

And now we can all move on to the real questions.

9. Florida's skill positions

In terms of receiving yards, Florida's top seven pass catchers are back. A position that has often been a weakness in recent years -- quarterback play isn't the only reason the team hasn't finished in the top 50 in passing yards per attempt since 2011 -- finally has high upside, with the potential to be as good as any other receiving corps in the SEC. Standout Antonio Callaway is back, along with an impact tight end in DeAndre Goolsby, a veteran in Brandon Powell and a rising star in sophomore Tyrie Cleveland.

Why is the unit a mystery? Callaway is suspended on Saturday.

The junior, who caught 54 passes for 721 yards last year despite subpar quarterback play, has frequently run into off-the-field trouble. Six others were suspended with Callaway, and freshman receiver James Robinson joined them this week. It's a lot of punished players, and none are more important than Callaway, a talented playmaker capable of providing the biggest spark for this offense. He would have been a valuable player to have to attack Michigan's new-look secondary. Cleveland, Powell and sophomore Josh Hammond are listed as the starting wide receivers on Florida's depth chart.

Update: This blurb initially merely covered the Florida receiving corps. Now it has to include the running backs, too.

Scarlett was by far the team's leading rusher last season, carrying the ball 179 times for 889 yards and six TDs. With Scarlett joining the long list of suspended Gators, sophomore Lamical Perine and senior Mark Thompson are next up on the depth chart, with freshman Malik Davis expected to play, too.

Due to Florida's continued off-the-field problems, perhaps this game is getting less unpredictable.

8. Michigan's quarterback situation

It's possible this isn't actually much of a mystery. As a first-year starter, Wilton Speight started 12 games, completing 61.6 percent of his passes for 2,538 yards, 18 TDs and seven INTs. Michigan's offense ranked only 61st in yards per play, but it scored 40.3 points per game, and the Wolverine were 9-0 before dropping three of their last four games by a total of five points. Michigan already showed it can win with Speight, even if he's not going to be any sort of All-America threat.

Nevertheless, there has been competition this offseason. While true freshman Dylan McCaffrey may be the future, the best challengers to Speight right now are senior Houston transfer John O'Korn and redshirt freshman Brandon Peters. Peters outplayed Speight in the spring scrimmage, but Harbaugh indicated this month that O'Korn -- who had a rough outing in place of the injured Speight vs. Indiana -- has been Speight's closest competition.

Harbaugh, of course, won't go any further, but for all the legitimate talk of a competition, it's hard not to see Speight as the overwhelming favorite.

7. Florida's run defense

The Gators have been more known for pass defense than run defense, but that doesn't mean they haven't been effective against opposing ground games. Still, thanks to a torn Achilles for safety Marcell Harris, the team's leading tackler, the top four tacklers from 2016 are gone, also including safety Marcus Maye and linebackers Jarrad Davis and Alex Anzalone. While sophomore MLB David Reese returns, he'll be playing behind a new-look line that loses tackles Caleb Brantley and Joey Ivie. Presumed new starters Taven Bryan and Khairi Clark are both juniors with experience, but they'll quickly be tested and put under pressure with the new faces at linebacker, too.

For all his faults, Muschamp left a fully stocked defensive depth chart for Florida a couple years ago, but a new wave of players are filling the depth chart now under new coordinator Randy Shannon.

6. Florida's secondary

Amazingly, it should still be a strength, and even if there are some bumps, they'll be aided by a stellar pass rush led by sophomore Jabari Zuniga and junior Cece Jefferson. But in addition to losing a valuable player in Harris to injury, Florida says goodbye to a pair of star cornerbacks in Quincy Wilson and Teez Tabor, plus a standout safety in Maye. All three were drafted in the first two rounds in April, and that's after Vernon Hargreaves and Keanu Neal were first-round picks in 2016. That's five premier NFL talents lost in two years, on top of saying goodbye to defensive coordinator Geoff Collins (new Temple head coach) and secondary coach Torrian Gray (Washington Redskins).

Despite all the turnover, there are three clear standouts returning. Cornerback Duke Dawson thrived in a nickel role and should make a smooth transition to a starting spot. Sophomore Chauncey Gardner won Outback Bowl MVP and can play either cornerback or safety, with the latter looking more likely because of Harris' injury. And Nick Washington started six games at safety last year and finished with 45 tackles in 10 games. Depth, however, has become a much more pressing question. The good news? Florida's schedule is barren of proven opposing passing attacks.

5. Michigan's secondary

Ten starters are gone from the Michigan defense, including eight drafted players: Jabrill Peppers, Taco Charlton, Chris Wormley, Jourdan Lewis, Delano Hill, Ben Gedeon, Ryan Glasgow and Jeremy Clark. No matter how much talent and experience is still on the roster, that is a lot to lose, and, if nothing else, depth will take a hit. And yet it's hard to feel concerned about the front seven, particularly the line. Rashan Gary, Bryan Mone, Maurice Hurst and Chase Winovich are all "new" starters, but they have all seen significant action. Hurst has All-America potential, and Gary was the No. 1 overall recruit in the class of 2016. Mike McCray is back at linebacker, and the front seven is in solid hands, even if the depth isn't nearly as proven.

Of greater concern is the secondary, which loses an All-American in Lewis, plus Clark, Hill, Dymonte Thomas and Channing Stribling -- not to mention the versatile Peppers. Players like sophomore Lavert Hill have high ceilings, but the secondary is much more of an unknown than the defensive line, even if both units lost all four starters. Like Florida, there is time to gel, as the best opposing passing games come in the second half of the season, but if the Gators' passing game is actually improved, even without Callaway, this will be an interesting test.

4. Michigan's receiving corps

Michigan's passing game was mostly serviceable last year, as Speight avoided mistakes -- 18 TDs, seven INTs -- and played well enough, at least before injury troubles in November. The Michigan passing game as a whole finished 41st in passer rating and 58th in yards per attempt, and now it loses tight end Jake Butt and wideouts Amara Darboh and Jehu Chesson. Those three combined for 138 catches for 1,908 yards, or 60.1 percent of the team's receptions and 69.2 percent of the team's receiving yards.

The leading returning receivers are Grant Perry (13 for 183) and fullback Khalid Hill (16 for 118). Harbaugh has recruited at a high level, and there's no doubt that there's plenty of talent available. Eddie McDoom could see a larger role after getting some action as a runner last year, and true freshmen Tarik Black and Donovan Peoples-Jones were both blue-chip recruits who enrolled early. Throw in names like sophomore Kekoa Crawford and true freshmen Oliver Martin and Nico Collins, and the potential here is high. Like the secondary, however, it's a mostly untested and unproven unit, and relying on a bunch of freshmen can't help but create volatility.

3. Michigan's offensive line

Harbaugh is known for building powerful football teams. That's exactly the type of identity he established at Stanford, even when he had Andrew Luck at quarterback. Last year's Michigan line was solid, as the team averaged 4.8 yards per rush, its best mark since 2011, but it was inconsistent and not as physically dominant as hoped. Gone are Erik Magnuson, Kyle Kallis and Ben Braden, and while all three were given All-Big Ten honors, none were actually drafted.

With Grant Newsome still recovering from a serious leg injury, the team will have three new starters joining senior Mason Cole (who has shifted between tackle and center in his career) and Ben Bredeson. While there's the potential for improvement, how quickly the line gels and becomes a team strength is an open-ended question. There are options, but they're unproven, making this a work in progress. It's a group that could eventually match or surpass the performance of the 2016 line, but there will surely be bumps along the way.

2. Florida's quarterback play

It's not uncommon for depth charts, particularly before the first game, to include an "or" between two players, indicating that there is no clear-cut starter -- at least not one that's been announced publicly. Florida took things to another level at quarterback: Its official depth chart listed Feleipe Franks or Luke Del Rio or Malik Zaire.

"Will all play? I don't know yet," McElwain said last week. "Will a couple of them play? I don't know yet. I know we will have somebody at the position."

At least some of the mystery was, somewhat surprisingly, cleared up on Wednesday. Rather than wait until kickoff to reveal the starter, McElwain announced that redshirt freshman Feleipe Franks won the job.

Franks was viewed as Florida's QB of the future, but he was a raw four-star recruit, and after he redshirted, Florida bringing in a graduate transfer wasn't exactly a vote of confidence. This summer, Zaire arrived to compete for the job. He flashed potential at Notre Dame after unseating Everett Golson but missed most of 2015 with an injury, then was unable to regain his job from DeShone Kizer. Zaire struggled in limited action last year, and in his Notre Dame career, he threw for 816 yards and six TDs and rushed for 324 yards and two TDs, showing off a strong arm and running ability.

Zaire presumably wanted to transfer somewhere where he could actually play, but his role is now even more up in the air. Franks also beat out Del Rio, who began his career at Alabama, transferred to Oregon State and then transferred again to Florida. He is the only player with experience at Florida, as he started six games but dealt with injury problems last year, completing 56.7 percent for 1,358 yards, eight TDs and eight INTs. 

While there are finally increased expectations for the Florida offense, which hasn't finished in the top 50 nationally in passer rating since the Tim Tebow era, it's hard to get fully on board just yet when the top receiver and running back are suspended for a big opening game and the quarterback position is still an unknown, given that Franks has never attempted a college pass. Michigan's defensive front will surely provide a stiff initial challenge.

1. The game outcome

Michigan is 3-0 against Florida, with all three matchups coming in bowl games since the turn of the century. The most recent meeting was at the end of 2015, the debut season for both Harbaugh and McElwain. With Florida's offense a mess by the end of the year, Michigan won the Citrus Bowl 41-7, out-gaining the Gators 503 to 273.

The Wolverines are four-point favorites in Vegas for Saturday's game, where it's expected that defense will also be the story (the over/under is 45). Michigan was the better team each of the past two years, and with both teams dealing with substantial attrition -- Florida's offense has plenty of experience, but the QB uncertainty and absence of Callaway and now Scarlett, too, overshadow everything else -- it's reasonable to see Michigan as a slight favorite. It's even more reasonable as Florida continues to suspend players.

Nevertheless, these are wild-card teams, talented enough to make a play for conference titles and top-10 rankings while possessing too many holes to make them frontrunners in 2017.

Their game against each other will not solve all of the mysteries, but on the second-biggest stage of college football's opening weekend, there will be nothing left for Michigan and Florida to hide.

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Contact Matt at matt.brown5082@gmail.com and follow him on Twitter @MattBrownCFB and Facebook.