The quarterback: the most polarizing figure on every football team's offense. There are those that are great and there are those that fans can't bare to watch because their performances are just too painful. But then there are those who have something to prove, a chip on their shoulders. Although we're at the tail end of the spring football season and camps are wrapping up, it's never too early to talk about these kinds of quarterbacks. Here are the five quarterbacks who have something to prove in 2015.

Jake Coker, Alabama, Sr.

This time last year Coker was the hottest commodity on the QB transfer market. Alabama had just lost AJ McCarron and had just hired Lane Kiffin to take over as the new offensive coordinator. Enter Coker who was dubbed the premature heir apparent as soon as he set foot on campus. However, after a grueling battle, Coker lost out on the starting job to Blake Sims. Well now that Sims is gone, Coker will once again enter his name into the Alabama starting QB sweepstakes. Coker figures to be the favorite this time around - again - as he goes up against a wealth of young, inexperienced quarterbacks. His time to shine is now and it's time for him to prove that he's worth all the hype that was bestowed upon him last year when his legend began.

Christian Hackenberg, Penn State, Jr.

When Hackenberg stepped on to the scene in 2013, he was one of the highest rated QB's in that recruiting class. Earning the starting gig in his freshman season, he went on to prove that he was indeed one of the top young signal callers in the game, throwing for 2,955 yards and 20 touchdowns. With his sophomore season came a new head coach in James Franklin and even higher expectations. Hackenberg suffered a bit of sophomore slump in 2014, showing flashes of brilliance - breaking the single-game passing yards record with 454 against UCF - but also showing signs of struggle, being sacked 44 times due to a weakened offensive line. Coming into 2015, Hackenberg can go one of two ways. He can revert back to the guy who has all the tools to be the no. 1 QB in the 2016 NFL Draft, or he can continue the roller coaster he started last season. 

Trevor Knight, Oklahoma, Jr.

Knight sort of finds himself in the same boat as Hackenberg in terms of dealing with the hype surrounding him. After shocking the world in the Sugar Bowl by beating Alabama, Knight was thrust into the spotlight and looked upon as a dark horse Heisman candidate for the 2014 season. Knight's accuracy was lacking early on and a neck injury sidelined him for the final three games of the season. Now Knight finds himself in the midst of a position battle against sophomores Cody Thomas and Baker Mayfield, the highly touted transfer from Texas Tech. To add to the level of difficulty, Knight has to learn a whole new offensive system under new coordinator Lincoln Riley. 

Maty Mauk, Missouri, Jr.

Mauk is the pure model of inconsistency. When he came on as an injury replacement for quarterback James Franklin in 2013 as a freshman, Mauk showed a lot of promise and looked like the next Heisman-contending SEC quarterback. After finally getting a chance to start in 2014, all of that seemed to fade away as Mauk looked like a completely different passer, completing 53.4 percent of his passes and throwing 25 touchdowns and 13 interceptions. There was one three-game stretch where he threw five picks and no touchdowns. Coach Gary Pinkel tends to remain loyal to his veterans, but could find himself forced to make a switch if Mauk doesn't perform better.

Chad Kelly, Ole Miss, RJr.

Other than Jake Coker, Kelly is probably the only other transfer that has made some ripples. He's also one of the most controversial transfers, carrying a lot of baggage that have others scratching their heads as to why Hugh Freeze would take this kind of behavior on. Kelly has had a share of run-ins with the law and was even dismissed from Clemson, being forced to play at East Mississippi Junior College last year. While there he did throw for over 3,900 yards and 51 touchdowns, so clearly Freeze is hoping the reward is much bigger than the risk in this case. And according to Freeze, Kelly isn't the favorite and someone else is ahead in the race. Sophomore Ryan Buchanan is currently leading the race per Freeze, but has just a slight advantage. Kelly needs to pull his act together if he hopes to show what he can truly do on the field if given the chance.