In the past three seasons, the challenges each winner of the Comeback Player of the Year award was tasked to overcome differed dramatically. Philip Rivers struggled mightily in 2012 by his standards, posting just the 21st-highest grade among QBs, but bounced back in a big way in 2013, jumping to fourth overall and a Comeback Player of the Year honor. Rob Gronkowski suffered a devastating injury late in the 2013 season when he tore his ACL in a game against the Cleveland Browns, but was healthy throughout the 2014 season and was PFF’s top-graded TE. Eric Berry was forced to leave the Kansas City Chiefs late in 2014 due to his battle with Hodgkin’s lymphoma, and remarkably returned to the field in 2015, where he posted the sixth-best grade among all safeties in the NFL.

Prior to Gronkowski (2014) and Berry (2015), a quarterback had won the award six straight seasons from 2008-2013. With this in mind, let’s take a look at five players who will likely contend for NFL Comeback Player of the Year in 2016.

1. Le’Veon Bell, RB, Steelers

Although the NFL has morphed into more of a running back-by-committee league in recent years, there are still a few backs that can rightfully earn the “bell cow” label, most notably Le’Veon Bell of the Pittsburgh Steelers.

For his career, Bell has been on the field for 80.8 percent of the possible snaps (for comparison purposes, Minnesota Vikings running back Adrian Peterson is at 66.5 percent for his career). He is truly a three-down workhorse, and one that is a rare breed in today’s game.

Unfortunately for Bell and the Steelers’ organization, a torn MCL midway through the 2015 season left Pittsburgh without one of the most dynamic playmakers in the NFL; a year which still resulted in 10-win regular season and a road playoff victory at Cincinnati.

Though he appeared in only six games, Bell earned the highest grade of any NFL running back this past season. Now healthy and part of one of the most explosive offenses in the league, there is little reason to doubt Bell will be a favorite to win Comeback Player of the Year this season.

2. Jordy Nelson, WR, Packers

Although the Green Bay Packers went 10-6 and won the NFC wildcard game at Washington before ultimately falling to the Arizona Cardinals in the divisional round, it seemed as if they never fully clicked without star wide receiver Jordy Nelson in 2015.

Nelson, who accounted for 183 catches, 2,833 yards, and 21 touchdowns in 2013/2014, was lost for the entire 2015 season when he tore his ACL in a preseason game against the Steelers. The Packers’ offense finished 15th in the league in points per game (23.0) and 25th in passing yards per game (218.9), just one year removed from leading the league in points per game (30.4) and ranking eighth in passing yards per game (266.3).

In terms of PFF grades, Nelson ranked second among WRs in both 2013 and 2014. Quarterback Aaron Rodgers, who was the NFL’s Most Valuable Player in 2014 with Nelson on the field, had a good—but not elite—season in 2015, finishing with the 12th-highest grade among QBs.

The return of a healthy Jordy Nelson should help Rodgers reclaim his status as one of the game’s best and make the Packers’ offense dangerous once again in 2016.

3. Andrew Luck, QB, Colts

From 2012–2014, Andrew Luck was not a top-tier quarterback, but certainly was in the discussion, posting PFF grades of that ranked 13th, ninth, and sixth, respectively. 2015 was a disaster season for Luck and the Colts, though, as he graded out as PFF’s 38th quarterback out of 38 qualifiers.

Luck’s season can largely be blamed on the various injuries he endured. It is believed that he sustained torn cartilage on two of his ribs early in the season, before suffering a lacerated kidney and a partially-torn abdominal muscle on a massive hit by Denver Broncos LB Danny Trevathan in Week 9 that ultimately ended his season.

Luck has been one of the most-pressured quarterbacks in the NFL since entering the league in 2012 as a result of poor offensive line play. In terms of pass-blocking efficiency, the Colts ranked dead last (32nd) in 2012, 29th in 2013, 21st in 2014, and 23rd in 2015.

To help the cause, the Colts selected Alabama center Ryan Kelly with the 18th overall pick in the 2016 draft. Kelly figures to be a significant upgrade at the position and a day-one starter (he surrendered no sacks and allowed just five hits and eight hurries the last two years in college). A healthy Luck and solidified offensive line should help the Colts regain their composure on offense in 2016.

4. Tyrann Mathieu, CB, Cardinals

A torn ACL is difficult to come back from once; Cardinals defensive back Tyrann Mathieu will be trying to do it for a second time in 2016.

Mathieu, who was in the conversation for Defensive Player of the Year before suffering the injury late in Week 15 at Philadelphia, tore his other ACL as a rookie in Week 14 of the 2013 season.

Viewed more as a safety coming out of college, Mathieu has transitioned into a hybrid defensive back for the Cardinals, one who has played more cornerback (particularly in the slot) than deep safety through the first few years of his career. In 2015, Mathieu played 512 snaps in coverage (56 percent), 367 of which came from the slot (40 percent).

PFF ranked Mathieu as the top cornerback in the NFL last year by a significant margin (91.6 overall grade, compared to Darius Slay's 87.7, the second-best mark). He was a key piece to a defense that ranked seventh in the league in points allowed per game (19.6), and his absence was evident down the stretch and into the playoffs.

Mathieu is expected to be ready at or near the beginning of the 2016 season, and should help lead one of the best defensive units in the league again, making him a legitimate contender for the Comeback Player of the Year.

5. Tony Romo, QB, Cowboys

Led by a dominant ground-and-pound rushing attack, a bend-but-don’t-break defense, and efficient quarterback play, the Dallas Cowboys were minutes away from the NFC Championship Game in 2014 before falling late to the Packers in the divisional round.

One year later, the Cowboys were a 4-12 team that was dismantled by injuries to key players, most notably quarterback Tony Romo. A broken collarbone sidelined Romo for two months, who returned with a win at Miami in Week 11, only to re-injure the same collarbone just a few days later against the Panthers on Thanksgiving.

Romo has been one of the most consistent quarterbacks in the league the last five years, earning season grades that ranked 11th, 10th, 11th, 13th, and seventh from 2010–2014 before his injury-plagued season of 2015.

While the injury history is a concern, Romo will return to arguably the best offensive line in football, an elite wide receiver in Dez Bryant (who is also overcoming a serious injury from last season), and a rookie running back who was taken fourth overall, Ezekiel Elliott.

There is reason to believe that Dallas will be much closer to their 12 wins of 2014 than their four of 2015, and if this is the case, Romo will deserve a lot of the credit and could be deserving of consideration for Comeback Player of the Year.