College football players across the country enter spring practice with the mentality that they have something to prove. But there are some cases in which that mindset makes more sense than others.

Here are 10 situations in the SEC in which players need to send a message, loudly and clearly:

Quarterback Chad Kelly, Ole Miss: Kelly is a classic “something to prove” prospect this spring. Talent is not the question with Kelly, who transferred from East Mississippi Community College in January. The problem is volatility. Kelly left Clemson last year under horrible terms, and then was arrested in December in Buffalo, New York, and faced multiple charges including assault and resisting arrest. Ole Miss has a vacancy at quarterback after Bo Wallace’s departure, and Kelly will compete for the job with DeVante Kincade and Ryan Buchanan. Kelly passed for 3,906 yards, 47 touchdowns and eight interceptions last fall. Now we’ll see whether he can keep his act together after Rebels coach Hugh Freeze gave him second and third chances.

Running back Keith Marshall, Georgia: Marshall was the more highly regarded prospect when he and Todd Gurley signed with the Bulldogs in 2012, and they formed a dangerous duo that fall. Marshall ran for 759 yards and eight touchdowns as a freshman but has barely played since suffering a knee injury five games into the 2013 season. Gurley’s gone to the NFL, but Georgia has Nick Chubb and Sony Michel at the top of the running back depth chart now. Where does Marshall fit in? He’s been out of the picture for so long, it’s tough to say at this point.

Quarterback Jacob Coker, Alabama: Most thought Coker would take over as Alabama’s starting quarterback last year when he transferred from Florida State. Instead, it was Blake Sims who grabbed the job and never gave it up. Sims is gone now, though, clearing the way for Coker to claim the position in 2015. Can he get the job done?

Wide receiver Ricky Seals-Jones, Texas A&M: Aggies fans expected superstardom when Kevin Sumlin’s staff signed Seals-Jones in 2013, but he missed almost all of his freshman season with a knee injury. Seals-Jones played in all 13 games last season, finishing with 465 yards and four touchdowns on 49 receptions. Those are fine numbers but nothing close to what A&M fans envisioned when he signed two years ago. He has plenty of time to develop into a star, however. Maybe he’ll take a step toward that level of production this year.

Gerald Dixon and South Carolina’s entire defensive line: No sense singling out Dixon here. South Carolina’s defensive front was horrible in 2014. The line’s ineffective play was the key reason why the Gamecocks tumbled from a spot as one of the SEC’s best defenses to one of the worst. Dixon and his fellow starters are on notice as the Gamecocks open spring practice. If they don’t play better, South Carolina’s coaches will have to give somebody else a chance. Last season wasn’t nearly good enough.

WR Nate Brown, Missouri: Missouri has to replace its top three receivers from last year, Bud Sasser, Jimmie Hunt and Darius White, all of whom were seniors. The Tigers will turn to a new collection of wideouts this year, led by Brown. The sophomore made just five catches for 45 yards a season ago, but his size/speed combination makes him the safest bet to make an impact this fall.

LSU’s quarterbacks: Last season was a mess at the quarterback position for LSU. Somebody -- either junior Anthony Jennings or sophomore Brandon Harris -- needs to take this job and run with it. Jennings completed just 48.9 percent of his passes while starting 12 of 13 games, but Harris’ lone start at Auburn was a complete dud. He’s a talented player, but Harris has to prove to Les Miles and his staff that he won’t make catastrophic errors if they put him on the field. He hasn’t convinced them yet.

Running back Alvin Kamara, Tennessee: Kamara was one of the nation’s most highly recruited running backs when he signed with Alabama in 2013, but he disappeared on the Crimson Tide’s depth chart and was twice suspended during his year in Tuscaloosa. Kamara transferred to Hutchinson Community College last season and rushed for 1,211 yards and 18 touchdowns in nine games. Now he has a second chance to prove that he’s an SEC-caliber back, forming what could be a dangerous one-two punch with Jalen Hurd at Tennessee. If Kamara can keep his head on straight, he has an excellent opportunity to make an impact with the Volunteers.

Quarterback Maty Mauk, Missouri: Mauk wasn’t the quarterback in 2014 that many expected after an impressive freshman season. He was inconsistent and prone to poor decision making at times. He passed for 2,648 yards, 25 touchdowns and 13 interceptions, which is not horrible, and helped the Tigers claim their second straight SEC East title. But Mizzou desperately needs its quarterback to improve upon his 53.4 completion percentage and become a more consistent performer as a junior.

Texas A&M’s defense: Texas A&M hopes John Chavis is the key piece that was missing over the past two years, when the Aggies featured one of the SEC’s worst defenses. The former LSU and Tennessee defensive coordinator has gotten results wherever he’s been, but Chavis has his work cut out at A&M. The Aggies were 102nd nationally (450.8 ypg) in total defense and tied for 75th in scoring defense (28.1 ppg). Considering how effectively the Aggies typically score, trotting out a defense that is simply better than awful might help them become more competitive in the tough SEC West.