The conference returns a number of experienced and talented quarterbacks, but for two of the ACC's top teams, there is an open competition at the position. Those competitions will define the spring for Florida State and Louisville and could define all of 2015. Those position battles highlight the conference's most intense competitions this spring.

1. Florida State starting quarterback

When Jameis Winston committed to the Seminoles, it was assumed the No. 1 high school quarterback would transition into the starting role after a redshirt year once EJ Manuel departed. There is not an obvious answer for who will follow Winston, however. Sean Maguire filled in admirably against Clemson under tough circumstances and against the top defense in 2014, but he still has much to prove. J.J. Cosentino was an ESPN 300 recruit and certainly has the build (6-foot-4, 234 pounds), but he redshirted as a freshman. De'Andre Johnson enrolled in January and could be a dark horse, but fellow freshman Deondre Francois, who will arrive in the summer, has the higher prep pedigree. John Franklin III could get some looks in the spring, but he spent most of last season at receiver.

Will Gardner passed for 1,669 yards with 12 touchdowns and just three interceptions in eight games for Louisville last season, but missed five games overall, including the final three. Andy Lyons/Getty Images

2. Louisville starting quarterback

You might have better odds hitting the superfecta at Churchill Downs two months from now than accurately pegging who the Cardinals will start in the season opener. Will Gardner, who took the majority of snaps in 2014, is recovering from a torn ACL. Reggie Bonnafon collected a handful of starts as a true freshman, but he could not wrestle the starting gig from Gardner long term. Kyle Bolin showed promise against Kentucky in the regular-season finale but struggled in the bowl game against Georgia. Tyler Ferguson has followed Bobby Petrino around recently, so the transfer should have the offense down. Making it tougher on the three spring participants is the lack of experienced receivers. That will be another interesting position battle.

3. Georgia Tech's running backs

The Yellow Jackets are losing seven of their top nine leading rushers at running back, so aside from Justin Thomas, Georgia Tech's crowded backfield will have several new faces. Broderick Snoddy is the most experienced but is recovering from a devastating leg injury suffered in November. Snoddy has lightning speed and is a home-run threat with the ball in his hands. Dennis Andrews had only 16 carries in 2014, but he averaged 6.6 yards per carry. The name to watch is C.J. Leggett, who redshirted as a freshman last season but was highly rated coming out of high school.

4. Boston College's starting offensive line

Former offensive line coach Steve Addazio had the luxury of coaching five seniors along the line at certain points in 2014. The obvious flip side is that now he has to completely retool the offensive line, and the spring is the ideal time to start working on that chemistry. Guard Harris Williams returns from injury, but there are a number of question marks around him. Dave Bowen could be a solid bet to start at one of the tackle spots. Senior Frank Taylor could step in at center. Aside from Williams, though, nothing looks to be set in stone.

5. Clemson backup quarterback.

The Tigers probably have the conference's best quarterback, but Deshaun Watson has struggled to stay healthy since enrolling at Clemson. He suffered three significant injuries his first season, the last a torn ACL that will cost him spring practice. A year ago, the Tigers still had Cole Stoudt, who had started a handful of games. If Watson is not ready for the opener or has to miss any time in 2015, the Tigers' season could be in jeopardy. Nick Schuessler is a redshirt junior but a former walk-on who has thrown only 10 career passes. Kelly Bryant and Tucker Israel are true freshmen who enrolled in January.

6. Miami running back

Duke Johnson, whose career will be celebrated at Miami for quite some time, is off to the NFL. Miami has a strong stable of running backs it can rely on to replace Johnson, but it remains to be seen who will get the majority of the carries. Joseph Yearby was one of the country's top running backs in the 2014 class and ran for more than 500 yards as a freshman. However, Gus Edwards could leave the spring with the starting gig. Edwards is a bigger back but is capable of running away from defenders. Mark Walton is enrolling in the coming months, and he was one of the top high school players in Florida last fall.