Regression is a rare thing in college football on an individual level.

Players tend to get better over time with additional experience, reps, weight room sessions and time to adjust to the college game. There’s a reason why upperclassmen are so valued and yearly awards lists are speckled with only the rarest underclassmen talent – 24 of 25 AP first-team All-American selections last season were upperclassmen.

That leads us to the idea of this story. 247Sports wanted to take a look at players in need of a bounce-back season in 2018. That would require a player having produced well in college before, only to see a significant drop in play later in their career. Seems like it’d be easy to find examples, right? Not really. Using PFF College data and its grading system as a benchmark, we combed through returning players and saw few extreme examples of regression. Players tend to improve over time, and good players rarely see a major drop in production barring injury.

But there were a few examples that can be cited. You won't find any quarterbacks here (and seriously, we looked — good QBs don't tend to take steps backward or they're already off campus) and not all positions are represented. But these are players who were considered strong contributors by PFF in 2016 who saw a significant decrease in quality of play last year.

They’re also players, by nature of their past play, who can potentially bounce back.

Rodney Smith, RB, Minnesota

2016 PFF Grade: 84.5 (11th)

2017 PFF Grade: 64.6 (180th)

Smith was a victim of Minnesota’s lack of a passing attack in 2017. The Golden Gophers finished 122nd nationally in passing offense and attempted fewer passes than any non-triple option Power Five team. That meant defenses keyed on the run, and Smith’s production dropped significantly as a result. A year after rushing for 1,158 yards, 16 touchdowns and 4.8 yards per carry, Smith averaged 4.3 yards a tote and managed just three touchdowns.

Smith should be Minnesota’s feature back as a senior, and there’s room for optimism. The Gophers passing attack can’t get any worse. It’ll likely get better with the addition of the nation’s top-ranked JUCO QB Victor Viramontes. P.J. Fleck offenses are traditionally explosive through the air, and Smith will benefit greatly from a little more room to breathe. A stat to watch with Smith is missed tackles. He forced 65 in 2016 but just 45 in 2017. If that number ticks up again and the Gophers passing attack provides some balance, expect Smith to clear the 1,000-yard mark.

Trayveon Williams, RB, Texas A&M

2016 PFF Grade: 77.8 (56th)

2017 PFF Grade: 41.1 (236th)

Williams could not have had a better start to the 2017 season: 22 carries, 203 yards and two touchdowns against UCLA. Then his production fell off a cliff. Outside of a 103-yard effort against Auburn, Williams would not again clear the 76-yard mark. Additionally, the home run hitter did not have a regular season rush of 20-plus yards outside of those two games – he had 10 such rushes in 2016 as a true freshman. Williams’ per carry average dropped from 6.8 to 4.6 as well.

There is still plenty of time for the rising junior to regain his freshman year form. He’ll benefit from a fresh start in a new system (though Jimbo Fisher’s offense will ask him to run between the tackles more frequently than he’s done in the past). Missed tackles, as they were with Smith, will be a telling stat. Williams managed just 20 in 2017 after forcing 43 in 2016. If that number returns to its 2016 range, Williams should again emerge as a star. Texas A&M needs him to. His backfield mate, Keith Ford, is off to the NFL.

Ahmmon Richards, WR, Miami

2016 PFF Grade: 83.4 (50th)

2017 PFF Grade: 73.5 (259th)

Richards’ PFF Grade drop wasn’t extreme like many players on this list. It’s relevant, though, because Richards went from potential superstar as a true freshman to simply solid contributor as a sophomore. Part of that attributable to health (Richards missed eight games last season) and suspect QB play (Malik Rosier struggled considerably at times), but Richards also had his issues. Richards actually saw a similar number of targets in 2016 and 2017 (77 vs. 63) despite his injuries. He also did considerably less with them. Richards reeled in 65 percent of his targets in 2016. In 2017 that number dropped to 39.6 percent. Richards also did less with the ball in his hands. A year after forcing 16 missed tackles, Richards totaled just four in 2017.

All of that said, Richards is still a clutch receiver — and a potential star. He’s speedy, explosive and a true vertical threat. With better health and a more consistent passer delivering him the ball (be it an improved Rosier or someone else), Richards should return to his freshman year production if not better.

Martez Ivey, T, Florida

2016 PFF Grade: 74 (184th)

2017 PFF Grade: 44.1 (283rd)

The former No. 2 recruit in the 247Sports Composite has had a better career than some might give him credit for. He's never been elite, which is disappointing given his former five-star billing, but Ivey started in Year 1 and anchored the middle of the Gator line at guard in the toughest conference in football. Then he moved to left tackle before his junior year … That experiment did not go well. Ivey did more than struggle – he collapsed. Ivey’s 44.1 PFF grade rated 283rd among qualifying tackles, and the 32 pressures he allowed led the Gators by 12. Ivey fared a bit better the last two weeks of the season when he swung back to guard. Yet even his great performance against UAB (84.5 per PFF) was mitigated by a 32.4 grade against Florida State.

There is room for optimism in regards to Ivey, however. He’s not likely to develop into a star left tackle, but returning to school for his senior season showed a willingness to improve. Plus, he’ll have a new offensive line coach, John Hevesy, to help provide a jolt. Hevesy’s been with Dan Mullen every step of the way through Mullen’s head coaching career, and Hevesy’s produced good offensive line units at every stop.

Physical tools will never be the issue for Ivey. Ivey may never turn into a tackle worthy of his five-star billing. But he can still be a good senior contributor for a Gator offense in need of a big turnaround.

T.J. McCoy, C, Florida

2016 PFF Grade: 79.2 (57th)

2017 PFF Grade: 41.3 (136th)

It’s not often I’ll include two players from the same school on a list like this, but Florida’s offensive line is a pretty unique situation. An average unit in 2016 devolved into a disaster in 2017. That’s in line with the nose dive the program took last year. But much of those offensive struggles can be traced to an o-line that floundered. The player in the middle of all that was McCoy. That’s baffling on its own considering how well McCoy played in spot duty the year before as a redshirt freshman. McCoy’s 41.3 grade finished 136th among qualified centers in 2017, which means he wasn’t a starting-caliber player with 130 teams in the FBS last season.

Like Ivey, there’s hope for McCoy. Hevesy’s presence should help bolster unit. A second year as the full-time starting center among a veteran group won’t hurt McCoy either. McCoy showed he was a capable SEC starter in 2016. Entering his fourth year on campus, McCoy needs to find that form again.

Freedom Akinmoladun, DE, Nebraska

2016 PFF Grade: 80.5 (64th)

2017 PFF Grade: 43.5 (508th)

A Big Ten All-Freshman team member in 2015 and a disruptive starter at defensive end in 2016, Akinmoladun looked to be trending toward star status entering his junior season. Yet that step never occurred. After totaling 32 tackles and four sacks in 2016, Akinmoladun’s numbers dropped to 24 tackles and two sacks last season. Part of the problem for Akinmoladun was the system. A 4-3 defensive end his first two years on campus, Akinmoladun found himself moved to 3-4 defensive end under Bob Diaco. That meant gaining weight and considerably more responsibility as a run stopper. That role mitigated his natural pass-rushing abilities, quickness and an explosive first step.

Nebraska will again field a 3-4 defense in 2017 under new defensive coordinator Erik Chinander. There are some differences in the scheme, however. Chinander’s overall aggressiveness should benefit Akinmoladun. Another year in the weight room and a second year in his new role should help, too.

P.J. Locke, DB, Texas

2016 PFF Grade: 81.8 (65th)

2017 PFF Grade: 47.4 (371st)

How good was Locke in 2016? Only Minkah Fitzpatrick allowed a lower passer rating when targeted among Power Five corners who returned in 2017. But Locke's follow-up season did not go nearly as well. Texas’ starting nickel, Locke graded out worse than all Longhorn defensive backs with 40-plus snaps. Locke, a physical defender who initially came to Texas as a safety, actually graded rather well as a run defender. Coverage is where he struggled, earning a 48.3 grade, 355th among qualified defensive backs nationally.

All of that said, the rising senior remains one of Tom Herman’s favorite players. Locke is considered a team leader and a tone setter for Texas. He started the spring as the Longhorns' starting nickel and is likely to retain the role.

Derrick Baity, CB, Kentucky

2016 PFF Grade: 82.6 (52nd)

2017 PFF Grade: 50.7 (338th)

You can track Baity’s production by looking at the way the Wildcats have defended through the air. Kentucky finished 35th nationally in passing defense in 2016 but dropped to 103rd in 2017. There were obviously other reasons for the Wildcats’ struggles, but they’re tracked best by looking at Baity’s play. After earning an 82.6 PFF Grade in 2016, he dropped to a 50.7 in 2017. His targets weren’t much different (67 vs. 73). Baity simply regressed.

Baity, who is out for the spring with a shoulder injury, does have a chance to bounce back as a senior. He’s started 29 games at Kentucky already and experience means something. Plus, Baity’s shown he can do it before.

Iman Marshall, CB, USC

2016 PFF Grade: 80.8 (86th)

2017 PFF Grade: 72.9 (234th)

Marshall, like Richards, didn’t show an extreme regression. But like Richards, Marshall’s drop in production is notable because of who he is. The No. 4 overall player in the 247Sports Composite from the 2015 cycle, Marshall is among the most naturally gifted players in the country. He flashed that as a sophomore, grading out as one of the Pac-12’s better defenders. But Marshall struggled a bit as a junior without Adoree Jackson on the other side of the field from him. Marshall didn’t come up with a pick after pulling in three the year prior, and the Trojans went from allowing 36 passes of 20-plus yards to 54.

Marshall opted to return for his senior year and will be a four-year starter for the Trojans. He remains immensely talented. I would be surprised if Marshall doesn't again emerge as a Pac-12 All-Conference type player.

Micah Abernathy, S, Tennessee

2016 PFF Grade: 79.8 (67th)

2017 PFF Grade: 47.4 (300th)

In terms of straight old-school production, Abernathy’s numbers saw an uptick in 2017. He went from 69 tackles to 81 and was a solid starter for the Vols all year. But look a little closer and Abernathy struggled. A year after PFF College assigned Abernathy a 78.8 coverage grade, Abernathy rated as a 46.3, which was 303rd among qualified safeties. He also came up with two fewer interceptions (from two to zero). Part of this is a product of a defense that struggled. It’s something you’ll often see when an entire unit has issues – look at Florida’s offensive line play for example. But Abernathy, in a year where fellow safety Nigel Warrior took a major step forward, regressed.

Like many players on this list, Abernathy will have a chance for rebirth in 2018 thanks to a coaching change. The biggest thing to watch with Abernathy is his decision-making. For example, he allowed a Florida receiver to get behind him against Florida leading to a season-altering Hail Mary loss for the Gators. If he can cut out moments like that, Abernathy could again be a critical contributor.