If you don't have a quality quarterback in college football, you probably don't have a very good team.

Of course, there are exceptions to every rule, but it's paramount teams get good play under (or behind) center if they're going to thrive. The growth and development of signal-callers can make or break you, and there are a lot of programs that need to see vast improvement there in 2021.

Some of the players on this list have been reason for excitement in the past, but their performances fell flat a season ago. Others just need the reps to turn things around. Then there are those who may generate hype, but the numbers don't back it up.

In a couple of cases, a change of scenery or a new coaching regime could work wonders for the player. 

All of these guys have the skill set to make things happen with their arm (and, in some cases, with their feet), and they will be relied on to make a difference for their teams in 2021. A few of them must win their respective position battles before that happens, though.

Let's take a look at a handful of college quarterbacks who you may not be talking about yet but are prime candidates to make major moves this season. 

Harrison Bailey, Tennessee Volunteers

This may be about Harrison Bailey, but it could just say "Tennessee's starting quarterback in 2021," because it's anybody's guess who is going to be the Vols' signal-caller now that Josh Heupel is at the helm.

One thing is clear, though: Whoever wins the job should improve dramatically if Heupel's success finding and developing quarterbacks such as Jordan Love, Drew Lock and Dillon Gabriel continues to hold true. The Vols have plenty of holes elsewhere on the team, but they have some strong QB candidates.

Hendon Hooker transferred from Virginia Tech and could be the answer for the immediate future, elite incoming freshman Kaidon Salter will get a chance, and Brian Maurer has starting experience, too. But perhaps the favorite to win the job is Bailey.

A season ago, the pure dropback passer had glimpses of quality play, but the offense was largely stagnant under Jeremy Pruitt and offensive coordinator Jim Chaney. The 6'5", 225-pound Bailey completed 70.6 percent of his passes as a true freshman for 578 yards, four touchdowns and two interceptions.

He has a lot of upside and should be a playmaker with his arm under Heupel, but he needs to win the job first. In February, UT offensive coordinator Alex Golesh told 247Sports' Patrick Brown it doesn't matter what a signal-caller's skill set is because they will adapt their system to fit it.

With a good, young group of receivers around him, Bailey (or insert competitor here) should have a much better season than he did a year ago. Tennessee will have its share of issues on the field and off, but quarterback production shouldn't be one of them in the Heupel era.

This may be the perfect scenario for the Marietta, Georgia, native to bust out and live up to the major expectations he had coming out of high school.

Chase Garbers, California Bears

Entering 2020, there was a lot of excitement around Chase Garbers, as California was a sleeper pick to contend in the Pac-12.

Things didn't exactly work out that way, and while the Bears went 1-3 with multiple cancellations in an odd, ugly season, the 6'2", 225-pound junior from Newport Beach, California, did not live up to expectations. He completed 62.5 percent of his passes for 771 yards, six touchdowns and three interceptions.

That was a bit of a step back considering how much he progressed during his first two seasons in Berkeley, racking up 28 total touchdown passes and looking like an impact player before an injury cost him part of his sophomore season.

Garbers didn't do a great job moving the ball downfield in 2020, averaging just 5.7 yards per attempt (down from 8.2 in 2019). Besides a 315-yard performance against Oregon State, he never threw for more than 183 yards.

Offensive coordinator Bill Musgrave didn't have much of a chance to work things out, and it showed in the stats. This spring is pivotal for the Musgrave-Garbers combo to get things moving in the right direction, and the early reports sound good, according to Bear Insider's David Bush.

"Chase is doing great, had a couple of good days," Musgrave told Bush. "He had his moments like all of us on offense. We all take all our lumps from time to time and learn from them."

There's no questioning Garbers' ability, and even if coach Justin Wilcox is known more for his defensive acumen, the Golden Bears need a much better performance at the quarterback position in '21. Look for Garbers to take a big step forward this season.

Graham Mertz, Wisconsin Badgers

The Graham Mertz Experience at Wisconsin has been interesting, to say the least.

When the Kansas native and elite quarterback prospect decided to join the Badgers, it was big news in recruiting circles. Coach Paul Chryst had never landed a player of his ilk, but he still had to wait his turn in 2019 behind Jack Coan.

Last year, Mertz got his opportunity to shine and started the 2020 season with a near-perfect performance against Illinois, completing 20 of 21 passes for 248 yards and five touchdowns in a sterling effort that made him look like a Heisman Trophy contender for a week.

Perhaps it was too much, too soon.

The rest of the season did not go well at all for the 6'3", 215-pound youngster, as the Badgers limped to a disappointing 4-3 record and Mertz became a turnover-prone, inconsistent performer, throwing just four touchdown passes and five interceptions the rest of the season after that great opener.

Mertz has a ton of ability, though, and after taking his lumps a season ago, he should be more ready in '21 with a better supporting cast around him. If Chryst relies on freshman running back Jalen Berger to help carry the team, Mertz can orchestrate a more balanced offense.

This is his team in Camp Randall, and he needs to settle down and quit trying to force the issue so much. If he does that and trims down on his mistakes, Mertz's terrific ability will shine through. He's ready to take a major step forward in 2021, and so is his team.

Adrian Martinez, Nebraska Cornhuskers

When Scott Frost came to Nebraska three years ago, he seemed set up to guide the same type of turnaround at his alma mater that he did at UCF. One of the key ingredients appeared to be the true freshman quarterback who turned into a playmaker right away.

But things haven't gone the way Adrian Martinez or his head coach would have liked since that promising 2018 start.

That year, the Fresno, California, signal-caller completed 64.6 percent of his passes for 2,617 yards, 17 touchdowns and eight interceptions. He also ran for 629 yards and another eight scores, looking like he was going to be a superstar for years to come.

Since then, however, Martinez has regressed. He's thrown just 14 touchdowns and 12 interceptions since then and has been jerked back and forth from the starting lineup and the bench due to ineffectiveness and inconsistency.

Following Luke McCaffrey's transfer to Louisville this offseason, however, this is Martinez's team again. Maybe without the weight of a starter competition on his back, he can relax and make things happen again for the Cornhuskers. 

The rushing numbers (626 yards in '19 and 521 last year) and touchdowns (14 on the ground the past two years) have never waned, and if Martinez can click with Frost and the coach can work on highlighting his signal-caller's strengths, this could be a big year again for Martinez.

If it doesn't happen now, it probably won't.

Cade McNamara, Michigan Wolverines

You may not consider Cade McNamara enough of a "sleeper" pick to be on this list, but considering the lack of respect the Michigan signal-caller has received, even after last season's hot start, he definitely is.

In limited action a year ago, he was far and away the Wolverines' most effective quarterback, completing 60.6 percent of his passes for 425 yards, five touchdowns and no interceptions. Even so, he was being overlooked again this offseason.

Joe Milton was the most talented quarterback on the roster, and while some expected him to win the job (again) this offseason, he wound up transferring. Even though Texas Tech's Alan Bowman is transferring to play for coach Jim Harbaugh, it shouldn't change the fact McNamara is the favorite to win the job.

Even with 5-star freshman J.J. McCarthy now on campus, McNamara is out there this spring, proving his doubters wrong again. Look for him to rebound from last year's shoulder injury and have a quality season leading Big Blue.

"The quarterback competition and level of play has been real interesting to see," senior offensive lineman Andrew Stueber told reporters, according to MLive's Aaron McMann. "Cade's finally started to take more of a commanding role. Obviously he played a little bit last season—but it's different when you think you have the starting job. Now you have command of the offense."

With Bowman coming in this summer, getting a head start this spring is huge for McNamara. He's going to claim the gig.

McKenzie Milton, Florida State Seminoles

The biggest wild card on this list could wind up being the feel-good, comeback player of the year story if he can take advantage of a major second chance.

Everybody cringed when, in 2018, dynamic UCF quarterback McKenzie Milton suffered a potentially career-ending gruesome leg injury against South Florida. It's been a long road back to the gridiron, but with Dillon Gabriel entrenched in Orlando, Milton needed a change of scenery.

He found it in Tallahassee, where second-year coach Mike Norvell needs a proven signal-caller to take over for a rebuilding Seminoles program. 

Jordan Travis, Chubba Purdy and Tate Rodemaker are the top contenders for the job, but if Milton can be anywhere near the gunslinging, playmaking dual-threat quarterback he was for the Knights pre-injury, he can compete at any level.

Yes, that's a huge "if," but who would bet against a competitor like Milton who has worked all the way back? It may not be an Alex Smith-type situation, but it's close.

A week into drills, things look good so far.

"I feel really good out there," Milton told reporters, according to ESPN.com's Andrea Adelson. "I don't feel any hiccups or anything like that running around. I feel comfortable out on the field, seeing the field. I feel like I need to continue to get in my playbook and continue to get reps, and not just live reps but mental reps, while other guys are taking reps. But I feel very confident out there."

Bo Nix, Auburn Tigers

Bo Nix has enjoyed a decent amount of hype during his first two seasons at Auburn, and though he's had some glimmers of heroics, his numbers have just been pedestrian so far.

With Gus Malzahn out and Bryan Harsin in, a fresh start may be just what Nix and the Tigers need.

A season ago, the 6'2", 213-pound program legacy threw for 2,415 yards, 12 touchdowns and seven interceptions and couldn't eclipse a 60.0 percent completion rate for the second consecutive year.

He did have more than 300 rushing yards again and seven scores on the ground for the second time, but the Pinson Valley, Alabama, product wasn't the threat many Auburn fans hoped he would be, with the offense stagnating throughout the year under Malzahn and coordinator Chad Morris.

Malzahn struggled to develop quarterbacks throughout his time on the Plains, so now with Harsin in charge (along with longtime SEC offensive coordinator Mike Bobo), Nix should thrive.

He has all the tools, and he already has shown his grit in some big games, but he just needs to put it all together and become a leader who can torch teams in all facets of the game.

There is already some buzz around youngster Dematrius Davis, who has Lamar Jackson tendencies, but it's far from time to give up on Nix. He's a poised, talented player who just needs to put everything together. The safe bet is he does that this year, and AU can finally rely on him to be a big-play guy.

Tyler Shough, Texas Tech Red Raiders

Tyler Shough posted some good numbers in his first year as Oregon's starting quarterback, but the more important the games got, the more he found himself on the sideline.

Boston College transfer Anthony Brown was worked into the rotation more by coach Mario Cristobal, and that led to the 6'5", 221-pound signal-caller leaving Eugene as quickly as he was placed in the starting lineup.

Now, he's the likely starter for Texas Tech after joining coach Matt Wells' program, and he is going to light up scoreboards in that system.

A season ago, Shough threw for 1,559 yards, 13 touchdowns and six interceptions, completing 63.5 percent of his passes. He shared time with Brown in a Pac-12 Championship Game victory over USC and a lopsided Fiesta Bowl loss to Iowa State, though.

He was more inconsistent as the season progressed, piecing together an up-and-down season in his only year leading the Ducks.

Henry Colombi may get the first chance to win the starting job in Lubbock, and with high-profile prospect Behren Morton coming in, it's no guarantee Shough wins the job. But he's by far the most talented player in that quarterback room, and it would be a shocker if he isn't ultimately the guy.

The big-armed signal-caller still has three seasons of eligibility remaining, so he could wind up being a huge pickup for the Red Raiders, who will have Sonny Cumbie calling plays. Things could get exciting, at least offensively, for a Tech team needing a major boost.

Jeff Sims, Georgia Tech Yellow Jackets

For all the excitement that swirled around Georgia Tech coach Geoff Collins rebuilding the Yellow Jackets when he was hired ahead of the 2019 season, a free-fall performance in 2020 led to several question marks.

It was never going to be an easy job transitioning from Paul Johnson's option attack, but Georgia Tech finished 3-7 and lost five out of six to end the year, including embarrassing losses (73-7 to Clemson, 48-27 to Boston College, 31-13 to Notre Dame) that showed just how far the program has to go.

Through it all, true freshman Jeff Sims was the quarterback. Though he definitely had his share of rough patches, the talent and potential for the Sunshine State signal-caller was evident.

He led the team with 1,881 passing yards and 492 rushing yards and accounted for 19 total touchdowns. However, he also threw as many interceptions (13) as scores.

Those are exactly the type of stats you should expect from a raw, dual-threat quarterback entering a tough situation on a rebuilding team in a conference that was on the upswing a season ago. Sims was never going to be a polished product right away.

Watch him progress in '21. With a season under his belt and more time learning the playbook, it won't just be all sheer athletic ability guiding him this year.

Sims is going to have a quality bounce-back season as a sophomore, and while the Yellow Jackets aren't ready to contend just yet, they'll take another step forward.

Skylar Thompson, Kansas State Wildcats

If Skylar Thompson could just stay healthy for an entire season, he may wind up packing stat sheets as one of the best quarterbacks in the Big 12.

Unfortunately for him and the Kansas State Wildcats, he hasn't been able to do that yet. 

A season ago, he was off to a terrific start, completing 62.5 percent of his passes for 626 yards and four touchdowns and rushing for three more scores, but he was lost for the season after injuring his shoulder against Texas Tech.

Before the latest setback, he'd already helped the Wildcats upset Oklahoma in the second game of the year. Thanks to the NCAA granting an extra year of eligibility due to COVID-19, Thompson gets another season in the Little Apple, and he could do big things.

Now, he's coming back for another season, and it may be just what third-year coach Chris Klieman needs to resurrect the once-proud program. Thompson has 30 career starts and has orchestrated consecutive wins over the Sooners.

Last year was forgettable for the longtime Wildcats leader thanks to the injury, but perhaps the win over OU is a sign of things to come. Kansas State's season spiraled as soon as Thompson went out, so his presence is a massive boost. Expect big things from him in his "extra" season in 2021.

All stats courtesy of CFBStats and Sports Reference. Recruiting rankings via 247Sports' composite rankings unless otherwise noted.

Follow Brad Shepard on Twitter, @Brad_Shepard.