NFL players with the most to prove in training camp in 2017

Abdullah played only two games last season due to injury, yet the Lions roll into training camp with him atop the depth chart. Now in his third season, Abdullah needs to show something in training camp to hold off Zach Zenner.

The Bucs were heavily criticized for using a second-round pick on Aguayo in last year's draft. After struggling in his rookie season, Aguayo will face competition for his job from veteran Nick Folk. His margin for error is especially small.

Allen takes over for Martellus Bennett as New England's No. 2 tight end behind Rob Gronkowski, but his role isn't a certainty. New England has a complicated offense for new players, and Allen's play has fallen off considerably since his first year in Indianapolis.

There's no question Bortles will be Jacksonville's starting quarterback going into the season, but they need him to play better. With the addition of first-round pick Leonard Fournette, the Jags offense has a chance to establish its new attitude during the exhibition season. Bortles will ultimately be the key.

Bryant missed all of last season due to suspension, but he returns this year with high hopes. The speedy wideout adds big-play ability that was missing from the Steelers last season, and we'll soon find out if he lost a step after a year away from football.

Charles had ACL surgery in 2015 and surgery on both knees last year. While doctors reportedly recommended that he hang up his cleats, Charles opted to sign with the Broncos. His play has been terrific over his career when healthy, but the 30-year-old back must prove in training camp that he has something left.

Cobb's explosiveness has declined over the last two seasons, averaging less than 11 yards per reception. Last year he missed three games and only finished with 610 receiving yards, falling behind Davante Adams in the pecking order. It could be a make-or-break year for Cobb as he fights for looks in training camp.

There's a new front office regime in Indianapolis, so Dorsett won't be getting the benefit of the doubt in his third season. The former first-round pick will battle Kamar Aiken for the No. 3 wide receiver job, and has to make strides after finishing with only 33 receptions last year.

The No. 1 overall pick in the draft last year, Goff looked like a rookie when he finally took the field during the second half of the season. Sean McVay was hired to develop Goff, and fans hope that turnaround can start during the exhibition season.

Even with opportunity available last year, Hackenberg failed to take the field for the Jets after going in the second round of the draft. Still, the signing of veteran Josh McCown isn't a huge roadblock for Hackenberg if he can show up as a viable option in training camp. However, some evaluators don't even think he's worth a roster spot.

After averaging less than four yards per carry over the last two seasons, the Bengals drafted Joe Mixon to challenge Hill. Now in his fourth season, Hill's lack of versatility could put him on the chopping block if he's unable to keep up with the rookie.

Hurns had more than 1,000 yards receiving in 2015, but fell behind Marqise Lee for the Jaguars last season. Injuries certainly hindered Hurns, but he needs to step in training camp with significant depth behind him.

The 49ers addressed their depth at running back by bringing in Tim Hightower, Kapri Bibbs, and Joe Williams. Hyde has often been injured during his brief NFL career, and there have been whispers that could fall on the depth chart if he doesn't impress new head coach Kyle Shanahan.

Ivory signed a lucrative deal with the Jaguars last offseason. After a bad first year, he could fall to third on the depth chart or even be released without showing better in training camp as Jacksonville is focused on rookie Leonard Fournette.

A former 2,000-yard rusher, Johnson signed a contract this July after playing only four games last season. He's hoping to win a role backing up David Johnson, but the Cardinals will cut the soon-to-be 32-year-old if he doesn't show well in camp.

A key part of Kansas City's defense, Johnson ruptured his Achilles' late last season. He's healthy heading into training camp, but has now suffered the injury in both ankles over the last three seasons and will turn 35 in November. There's reason to be concerned that Johnson's play will fall off, so he will have to prove otherwise in training camp.

Lynch came out of retirement to join his hometown team, potentially taking over for Latavius Murray as Oakland's starter. Now at age 31, Lynch played only seven games in 2015 due to back issues, and some believe that he's now over the hill. Lynch should have to earn the starting job.

Lynch will battle Trevor Siemian for the starting quarterback job in training camp. He looked overmatched when he was thrust into action during his rookie season.

Newton had a terrible 2016 season while playing through injury and had shoulder surgery during the offseason. Carolina added support for Newton by drafting Christian McCaffrey and Curtis Samuel, but there will be plenty of nervous Panthers fans if Newton flounders during the exhibition season.

Off-field concerns caused Nkemdiche to fall to 29th overall in the 2016 draft, and the fall seemed justified after his terrible rookie season. Nkemdiche made only one tackle in five games, but the Cardinals will be relying heavily on him after losing Calais Campbell to free agency.

Peterson played only three games last season due to a knee injury. While he seems like a great fit in New Orleans under head coach Sean Payton, it remains to be seen what Peterson has left at age 32. The Saints have plenty of alternatives of Peterson looks slow in training camp.

Savage will battle first-round pick Deshaun Watson for the starting quarterback job in training camp. The quarterback position has been a black hole for the Texans recently, and Savage has yet to prove he can be a long-term starter.

Treadwell looked lost in his rookie season, making only one reception despite going 23rd overall in the draft. The Vikings added Michael Floyd to Stefon Diggs and Adam Thielen in the offseason, creating an uphill climb if Treadwell wants significant snaps this year.

Watt missed nearly all of last season due to a back injury that required two surgeries. He claims to be healthy heading into training camp, but it remains to be seen if he can be the same dominant player that he was before the injury.

The seventh overall pick in the 2015 draft, While has played only four games over two seasons due to injuries. Chicago let star wideout Alshon Jeffery walk in free agency, so White will be relied on to make a huge leap forward. With a new quarterback, the Bears need White to get up to speed early in training camp.