The Biggest X-Factors of the College Football Playoff

Want star power? The College Football Playoff certainly isn't lacking any.

The Rose Bowl (No. 2 Oregon vs. No. 3 Florida State) and Sugar Bowl (No. 1 Alabama vs. No. 4 Ohio State) feature an eclectic mix of top-tier coaches, contrasting philosophies and future NFL players—all on the biggest stages.

Compelling television, it should be.

Which players will be X-factors in their respective January 1 games? It's tough to compile a short list from so many big names, but the following players were selected because of key matchups and important positions. Put another way, these are players whose teams wouldn't quite be the same without them.

The following list features two players—one for defense and one for offense—from each of the four teams.

Oregon Quarterback Marcus Mariota

Ben Margot/Associated Press

Oregon quarterback Marcus Mariota is the Heisman Trophy winner. How can he not be considered an X-factor?

The best player in college football has been so consistently good this season that even great games seem pedestrian. He leads the nation in yards per passing attempt (10.2) and accounts for 342.5 yards per game.

All of that is even more impressive when you consider this Ducks offense lacks the supporting star power that it's had in past years.

However, Mariota has thrown to some wide-open receivers against some awful defenses, most notably Cal, Colorado and Washington State—all of which rank 99th or worse in defense.

That's not to say he hasn't been tested at all—he threw for 318 yards and three touchdowns against Michigan State in September—but how he plays against an athletic defense that matches up well will be interesting.

Can Mariota make more tight-window throws? How much does he contribute in the running game? He's the cornerstone of the offense, for sure. If he's the best player on the field in the Rose Bowl against Florida State, the Ducks have an excellent chance of winning.

Florida State Running Back Dalvin Cook

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From last year to this year, there's no doubt that Florida State quarterback Jameis Winston has shouldered more responsibility for the offense.

At some point, though, even Winston needs help. That's where freshman running back Dalvin Cook comes into the picture. Cook wasn't a star right away, but rather worked his way into a more prominent role down the road because of injuries.

“Well, I don’t call it a 'late-season emergence,' we just started getting him the ball more at the end of the season,” Winston told reporters about Cook. “I cannot wait to see what he’s going to do over the years. His vision, his speed, he dominates that."

Cook gives Florida State a spark in the running game that it doesn't have with Karlos Williams. The speedy freshman had over 100 rushing yards in each of the last two games for FSU (144 against Florida and 177 against Georgia Tech).

While much of the focus will be on Winston and the passing game, Cook has a chance to be a difference-maker on the ground.

Ohio State Quarterback Cardale Jones

Darron Cummings/Associated Press

He's making his second career start. In the playoffs. Against top-ranked Alabama. Yeah, Ohio State quarterback Cardale Jones is probably important.

Ohio State head coach Urban Meyer and offensive coordinator Tom Herman haven't received nearly the credit they deserve for developing not one, but two backup quarterbacks into touchdown machines.

Jones was superb in his debut, a 59-0 win over Wisconsin in the Big Ten title game, throwing for 257 yards and three touchdowns.

Alabama's defense is obviously better with just 16.6 points per game allowed. The Tide also lead the nation with just 2.81 yards per rush allowed. If Buckeyes running back Ezekiel Elliott can't get going, Ohio State's hopes could rest on Jones' arm.

Can Jones exploit a more vulnerable Alabama pass defense? Will he be rattled or cool and collected? His chemistry with the offense's wide receivers and offensive line will be tested.

Oregon Cornerback Troy Hill

Rick Bowmer/Associated Press

With star Oregon cornerback Ifo Ekpre-Olomu out with a knee injury for the postseason, fellow Ducks corner Troy Hill has big shoes to fill.

Against Florida State, it's possible Hill and/or redshirt freshman Chris Seisay will be matched up against receiver Rashad Greene. Greene leads the Seminoles by a country mile in receptions (93).

But Hill is the redshirt senior, the guy who has been there and done that. Against an offense that averages 300 passing yards per game with one of the most accurate quarterbacks in the country, Hill is going to have to have a huge game.

Alabama Safety Landon Collins

Brynn Anderson/Associated Press

There aren't many weaknesses in Alabama's game right now. If there is one, though, it's preventing the deep ball on defense.

Auburn torched The Tide or 456 passing yards in the Iron Bowl, and Alabama allowed several busted plays by Missouri to go for big gains in the SEC Championship Game. That should have Ohio State thinking big.

Quarterback Cardale Jones is making just his second start for Ohio State, but this offense has big-play ability as well with wide receiver Devin Smith.

It's going to be up to veteran defensive backs like Landon Collins to keep those big pass plays to a minimum.

A problem for Alabama has been allowing receivers to get behind the coverage. As a safety, Collins is the last line of defense for the Tide. If the Sugar Bowl turns into a shootout, Collins is going to be an X-factor forced to make key stops.

Ohio State Defensive Tackle Michael Bennett

Darron Cummings/Associated Press

Ohio State defensive end Joey Bosa is going to get the attention because he plays a stat-friendly position and is excellent at it. Bosa leads the team in sacks (13.5) and tackles for loss (20.0).

But don't underestimate how important defensive tackle Michael Bennett is to the Buckeyes' chances of stopping Alabama's offense. Bennett is part of a physical defensive line that is arguably the best in the country.

Bennett's job is to prevent Tide running backs T.J. Yeldon and Derrick Henry from breaking loose. Alabama spreads the ball around much more now that Lane Kiffin is the offensive coordinator, but this is still an offense that runs the ball about 56 percent of the time.

In fourth quarters this season, Alabama has rushed for 882 yards and 5.62 yards per carry. That's better than the Tide's performance in any other quarter in those respective categories. 

The challenge, as Brian Bennett of ESPN.com points out, is for the defensive line to stay fresh during the entire game.

Florida State Cornerback P.J. Williams

Lynne Sladky/Associated Press

You know all of those video game passing stats Oregon quarterback Marcus Mariota has accumulated? It's going to be someone's job to make sure that doesn't continue in the Rose Bowl.

That someone is Florida State cornerback P.J. Williams.

Williams is second on the Seminoles with 10 passes broken up and is listed by Bleacher Report's Matt Miller, along with FSU corner Ronald Darby, as one of the best corners eligible for the 2015 draft.

The truth is Florida State's secondary is an important unit in the Rose Bowl against the Ducks. In addition to slowing down Mariota in the passing game, the Seminoles' defensive backs will have to show they can shed blocks if Oregon tries to run outside. 

That could be dependent on whether Florida State dominates the Ducks up front at the line of scrimmage.

According to Andrew Greif of The Oregonian, Oregon offensive coordinator Scott Frost called Williams the "fastest cornerback" he's seen this season. That presents a matchup problem for the Ducks.

Alabama Tackle Cam Robinson

USA TODAY Sports

Alabama's offensive line is a veteran group, but the exception is tackle Cam Robinson. As a freshman, Robinson is nevertheless an important player who sets the edge in pass protection.

Against Ohio State, Robinson is going up against defensive end Joey Bosa and/or Steve Miller. If the matchup is against Bosa, keep an eye on it.

Beside obvious matchups—Amari Cooper versus Ohio State's secondary, Cardale Jones versus Alabama's pass-rushers, etc.—this is the most important because it affects whether Tide quarterback Blake Sims is running for his life or not.

Alabama is the best team in the SEC in sacks allowed with just one per game, but it will go up against a defense that averages three sacks a game. That's the best mark in the Big Ten.

Something has to give.

Ben Kercheval is a lead writer for college football. All stats courtesy of cfbstats.com.