Stephania Bell examines how long it will take for J.J. Watt to recover from back surgery and what his status for the start of the season looks like. (1:29)

As training camp commences around the league, NFL Nation analyzes the injury question marks looming for each team.

AFC East | AFC North | AFC South | AFC West

NFC East | NFC North | NFC South | NFC West

AFC EAST

Until the injury bug hits the Bills again, there's no question about this one: It's wide receiver Sammy Watkins. The Bills' third-year wideout has battled injuries throughout his career and took another hit this offseason, when he needed surgery to repair a broken bone in his foot. He and coach Rex Ryan have maintained that Watkins will be ready for the start of the regular season, but Watkins' return to practice -- and if it's during training camp -- remains up in the air. -- Mike Rodak

The Dolphins have high hopes for their offensive line, but much of that rests on starting right tackle Ja'Wuan James coming back at 100 percent this season. The former 2014 first-round pick suffered a toe injury that forced him to miss nine games last season. The offensive line was forced to shuffling in replacements and never recovered, allowing 45 quarterback sacks. -- James Walker

Receivers Julian Edelman (left foot) and Danny Amendola (ankle, knee) didn't practice in the spring after having offseason surgery, but they are expected to serve as two of the team's top three pass-catchers this season. That assumes no setbacks, so this will be one important storyline to monitor throughout training camp. -- Mike Reiss

Muhammad Wilkerson, who just received a new $86 million contract, probably will begin camp on the physically unable to perform list as he continues to rehab a surgically repaired broken leg. The team will bring the Pro Bowl DE along slowly, employing a plan that will get him ready for Week 1. Wilkerson, who is running four days a week, vows to be ready for the opener. Meanwhile, LT Ryan Clady (knee), who missed last season for the Broncos, will be monitored closely. He should be cleared for contact drills. Ditto for CB Darrelle Revis (wrist). -- Rich Cimini

AFC NORTH

Take your pick: linebacker Terrell Suggs or wide receivers Steve Smith Sr. and Breshad Perriman. The Ravens are hoping Suggs can come back from an Achilles injury suffered in Week 1 last season, but the team is offering no guarantee and Suggs hasn't spoken to reporters in 10 months. Smith will sit out for the entire preseason while he continues to recover from an Achilles injury; the receiver says he's day to day. And the Ravens breathed a sigh of relief when Perriman avoided season-ending knee surgery, but his slow recovery last season makes him a question mark for training camp. -- Jamison Hensley

Without question, tight end Tyler Eifert's recovery from a May ankle surgery is the Bengals' biggest injury concern entering training camp and the regular season. We already know the likelihood of him playing this preseason is zero, and the chance he returns in time for the season opener at the New York Jets is hovering dangerously close to zero. What's most troubling about Eifert's injury is that it didn't come in a Bengals regular-season or playoff game. It happened in the Pro Bowl -- the first of Eifert's career -- when he was overthrown on a pass in the back of the end zone. Expect Cincinnati to take his rehab very slowly, meaning he may not be back until a couple of weeks into the season. -- Coley Harvey

Cornerback Joe Haden is vital to the Browns' success on defense. Haden is coming off ankle surgery and needs to show the same quickness and explosiveness that made him one of the league's top corners. With Haden playing well, the Browns can stick him on the opposing team's best pass-catcher. If he's out or struggling, the drop-off is significant and the defense struggles. -- Pat McManamon

Even with Le'Veon Bell facing a four-game suspension to start the season, all eyes will be on his health during training camp. He spent the offseason training in Miami with hopes of running and cutting without hesitation once camp starts. The Steelers will be cautious with Bell, who's still 10 months removed from MCL and PCL tears in his knee. -- Jeremy Fowler

AFC SOUTH

Until last week, the biggest injury question mark was left tackle Duane Brown, but now J.J. Watt's availability for the start of the season is in question. Watt had back surgery to deal with a herniated disc and will start training camp on the physically unable to perform list. It's unlikely the Texans will keep him on the regular-season PUP, which would make him miss six games. But the first two games of the season could come before Watt's recovery is finished. -- Tania Ganguli

Defensive linemen Henry Anderson (knee) and Arthur Jones (ankle) are both coming off injuries that caused them to miss some or all of the 2015 season. But Jones' status is the bigger question mark. He has played only nine games in his two seasons with the Colts and will miss the first four games in 2016 with a PED violation. Jones' effectiveness during training camp will provide a glimpse into how his ankle is progressing. Jones, who signed a five-year, $33 million contract in 2014, missed all of the offseason workouts as he continued to work his way back from the injury. -- Mike Wells

The Jaguars signed LT Kelvin Beachum to compete with Luke Joeckel (and most likely win the job), but Beachum is coming off a torn ACL and didn't participate in OTAs and minicamp. It's not known when he'll be cleared to participate in camp, either. The job may go to Joeckel, who has been an average player since being taken second overall in 2013. -- Mike DiRocco

Outside linebacker Kevin Dodd, the 33rd pick in the draft, had surgery in late May to insert a screw in his right foot to repair a stress fracture. The Titans said at the time it was a preventative measure, and they expected he would be ready for the start of training camp on July 30. But they will certainly be cautious with a player who could be a third edge-rusher behind veterans Derrick Morgan and Brian Orakpo. -- Paul Kuharsky

AFC WEST

This is really a two-part question for the Broncos. They are counting on Ty Sambrailo, who suffered a season-ending shoulder injury in Week 3 last season, to be fully ready by the start of the regular season. The Broncos took a measured approach to Sambrailo's work in the offseason program, but he is expected to be ready to take part in training camp as he figures to move from tackle to starting guard in Denver's revamped offensive line. The Broncos will also have their eye on DeMarcus Ware, who missed five games with back troubles last season and was held out for much of the offseason program with back pain. The Broncos will take it slow with Ware in training camp and hope he can be ready by September. -- Jeff Legwold

Linebacker Justin Houston had ACL surgery in February and is unlikely to be available when the Chiefs begin training camp on July 30. But the Chiefs have been optimistic that Houston, who has led the Chiefs in sacks in each of the past five seasons, will be available at some point during the regular season. -- Adam Teicher

This is a dual proposition, really, with both safety positions needing to answer the injury question. Free safety Reggie Nelson, whose eight interceptions with the Bengals last season were tied for the league lead, sat out the offseason practices with an undisclosed ailment. And first-round strong safety Karl Joseph, who had five picks in four games at West Virginia last fall, also sat out rehabbing his knee injury. The Raiders rebuilt their secondary with Nelson and Joseph as the last line of defense. -- Paul Gutierrez

Running back Melvin Gordon looked good during the end of offseason work and is expected to be fully healthy at the start of training camp for the Chargers. But whenever a player has microfracture knee surgery, as Gordon did in January, there will be reasons for concern. So Gordon's return to health warrants monitoring during exhibition play. -- Eric D. Williams

NFC EAST

The Cowboys' success in 2016 will hinge on Tony Romo. He played in just four games last season because of a twice-broken left collarbone. With Romo, the Cowboys went 3-1. Without Romo, they went 1-11. Romo's offseason included a surgery to his collarbone, but it also included him taking part in every practice in the spring. There is no question regarding Romo's availability for the season. The quarterback's favorite target, Dez Bryant, did not go through a full offseason of practice because of January surgery to his right foot. But he will be cleared for camp. Bryant and Romo played together in just one full game last season. If they both can return to 2014 form, the Cowboys will be among the NFC's best. -- Todd Archer

This is a no-brainer. Nobody, not even the Giants, knows what to expect from wide receiver Victor Cruz. He has missed 26 straight games and has played a grand total of six quarters with Odell Beckham Jr. over the past two seasons. The Giants can't be sure if Cruz can make it through an entire practice, nevertheless a game or the entire season. But if he does, it can take their offense to a different level. -- Jordan Raanan

Left tackle Jason Peters missed two games last season and was limited in several other games because of a pinched nerve in his back that caused pain in his legs. Peters stands to benefit from new coach Doug Pederson's approach -- no more no-huddle offense, chances to rest up during the practice week -- but time is not on the 34-year-old's side. While the Eagles have their next left tackle in Lane Johnson, Peters' absence would disrupt the line by forcing a backup to play right tackle. -- Phil Sheridan

It was Junior Galette, until he tore his right Achilles on Sunday, ending his season before camp even began. But now the injured player to watch is left guard Shawn Lauvao. He played well in his three games before hurting his foot last season, but has had multiple surgeries on both feet since October. If he's fully recovered, he'll give the Redskins a guard who can move. If not, Spencer Long and Arie Kouandjio will compete for his job. -- John Keim

NFC NORTH

Wide receiver Alshon Jeffery sat out seven games last season because of calf, hamstring, groin and shoulder injuries. The pressure is on Jeffery to stay healthy in 2016 after he and the Bears were unable to reach a long-term agreement on a contract extension. Jeffery, who will play under the franchise tag in 2016, has to prove he can shake the injury bug to secure a massive payday next offseason. He will be monitored closely in training camp after he opted to skip the club's voluntary offseason program in the spring; Jeffery instead trained in South Florida. -- Jeff Dickerson

Ameer Abdullah sat out the offseason recovering from shoulder labrum surgery, and Detroit is depending on the second-year running back to be the team's featured ball carrier. Considering the Lions' other major backs -- Stevan Ridley and Zach Zenner -- are also coming off injuries, any delay in Abdullah's recovery could spell trouble. Theo Riddick is healthy, but he's still primarily a pass-catcher. The Lions need a healthy Abdullah to achieve any sort of balance this season; Lions GM Bob Quinn said Abdullah should be ready for the start of training camp. -- Michael Rothstein

The Packers are playing it safe with Jordy Nelson, who was placed on the pysically unable to perform list and won't be on the practice field when camp opens. The Pro Bowl receiver did not practice at all during the offseason program -- except for catching some passes from Aaron Rodgers off to the side in addition to his rehab work. Nelson is 11 months removed from the torn ACL that cost him all of the 2015 season, but the Packers are typically conservative with how they handle injuries. -- Rob Demovsky

Center John Sullivan is returning from two back surgeries that kept him out all of last season. He said he made it through OTAs and minicamp "unscathed," and believes he'll be ready for training camp. Time will tell, though, whether the 31-year-old will make it through the full season and regain his starting job after Joe Berger filled in admirably for Sullivan last season. -- Ben Goessling

NFC SOUTH

Maybe the biggest question mark for the Falcons from an injury standpoint is the health of Vic Beasley Jr.'s right shoulder. The outside linebacker and pass-rusher insisted the torn labrum he dealt with last year didn't affect his play and didn't require offseason surgery. Beasley maintains the shoulder is healthy. But if the injury resurfaces, it could be a cause for concern, considering how much the Falcons will count on Beasley's pass-rush ability this season. -- Vaughn McClure

Wide receiver Stephen Hill suffered an ACL tear in training camp that was actually worse than the one that ended wide receiver Kelvin Benjamin's sophomore season. Benjamin appears ready to go when training camp begins, but Hill might be limited early. A second-round pick by the Jets in 2012, this might be Hill's last chance to prove himself. -- David Newton

CB Keenan Lewis was arguably the Saints' defensive MVP from 2013-14, when he was playing at a Pro Bowl level and matching up routinely against top receivers. But his 2015 season was derailed by a summer hip injury that limited him to just six games and zero starts. Luckily for the Saints, Delvin Breaux emerged as a No. 1-caliber cornerback last season. But he needed a lot more help, and the Saints' overall pass defense was abysmal in 2015. A healthy Lewis could make a huge difference. -- Mike Triplett

Wide receiver Louis Murphy suffered a torn ACL in Week 7 against the Redskins and underwent surgery, effectively ending his season. He also did not participate in any of the team's mandatory minicamp practices. The Bucs really need a No. 3 receiver behind Vincent Jackson and Mike Evans, and Murphy has the versatility to line up in the slot and outside, along with starting experience. Given the nature of his injury, his position and his age (29), this warrants attention. -- Jenna Laine

NFC WEST

Safety Tyrann Mathieu is rehabbing his second ACL injury in three seasons. He tore it in Week 15 last season, missing the final two games of the regular season and the Cardinals' run to the NFC Championship game. While this injury isn't as complex as his first knee injury, which included his ACL and LCL, it's still No. 2 for the Honey Badger during his NFL career. This raises concern about his durability and puts the Cardinals in the precarious position of handling his return the right way. They don't want to push Mathieu to return too early, but they need him on the field as soon as possible in 2016 to make a run at Super Bowl LI. -- Josh Weinfuss

For the Rams' vaunted pass rush to live up to its potential, defensive end Robert Quinn needs to return to the dominant form that had him in the discussion among the league's top pass-rushers. Quinn is coming off back surgery that kept him out of eight games last season, and the team is bringing him along slowly. During the offseason program, Quinn was limited in what he could do on the field but did get back to a normal weight room regimen. He also returns with a bit of a chip on his shoulder, telling me that he'd like to remind the league just how dynamic he can be. "I'm not the first to have an injury or overcome an injury but not having half the season, of course you get put into the shadows a little bit," Quinn said. "I don't need other people to motivate me. Seeing some of that stuff might somewhat add some fire, but at the end of the day, I have got my personal goals I want to achieve and that would turn the doubters into believers." -- Nick Wagoner

Biggest injury question mark in Santa Clara, thy name is Colin Kaepernick. With an exclamation point! At his zenith, which was a mere two offseasons ago, Kaepernick was dubbed as one of the greatest quarterbacks in league history. After three surgeries -- left shoulder, right thumb, left knee -- a trade request that fell on deaf ears and the hiring of a new coach in Chip Kelly, the dual-threat signal-caller is far behind Blaine Gabbert in the starting QB competition. -- Paul Gutierrez

The Seahawks are counting on Thomas Rawls to carry the load in 2016, but the running back is recovering from a fractured ankle injury that included ligament damage and ended his rookie season in December. Rawls said he expects to be ready for training camp, but the team has said it has no intentions of rushing him back. The goal is for Rawls to be ready to go in Week 1, and every indication from Pete Carroll suggests that the running back will be on the field for the opener. -- Sheil Kapadia