Teams have spent months addressing their weaknesses, but they each still face daunting questions that need to be answered. Can Carson Wentz regain the MVP form he displayed before a knee injury ended his season? Is Dak Prescott the seemingly surefire future star who took the league by storm in 2016 or the interception-prone QB who faded down the stretch in 2017? Our NFL Nation reporters identify the story that could define the season for all 32 teams.
Showing that making the playoffs last season was not a fluke
The Bills snapped a 17-year postseason drought last season, but they were a flawed team that finished near the bottom of the league in both passing offense and rushing defense. They tried to address those areas by trading QB Tyrod Taylor and signing DT Star Lotulelei to a $50 million contract this offseason, but the offense remains a concern. The unexpected retirements of center Eric Wood and guard Richie Incognito could hurt the offensive line, while nobody knows what Buffalo will get this season at quarterback. Whether it is AJ McCarron, Nathan Peterman or rookie Josh Allen under center, the Bills could struggle to meet the high bar they set last season. -- Mike Rodak
Is Ryan Tannehill still the quarterback of the Dolphins' future?
Miami seems to be at a crossroads, teetering on the brink of another rebuild. In what will be his sixth season, Tannehill must not only show that he is recovered from an ACL injury that wiped out his 2017 season, but also prove he can take another step forward after posting a 93.5 passer rating and making the playoffs for the first time in 2016. If Tannehill and the Dolphins regress, it might be time for a new direction for the Dolphins. -- Mike Rodak
Tom Brady and Bill Belichick's relationship
The most successful quarterback/coach partnership in the NFL hasn't been together this offseason as Brady has remained away from voluntary work, sparking questions about whether all is well between Brady and Belichick after a season in which Brady's personal trainer, Alex Guerrero, had his access curbed at Gillette Stadium. Brady has said he is taking the time to be with his family and three children, while Belichick said he is talking only about the players who are present at OTAs. How big of a deal will this ultimately be to the team's success? -- Mike Reiss
Sam Darnold's development
It will be a huge factor in determining whether the season is a success. His bid for the starting job will be an ongoing theme, from the first day of training camp to his inevitable promotion. People in the organization believe he has the goods to be the Week 1 starter, but coach Todd Bowles won't rush him. How quickly they elevate him to the starting lineup will say a lot about where the Jets believe they are as an organization. -- Rich Cimini
Will this be the end of the John Harbaugh-Joe Flacco era?
Over the past 10 years, Harbaugh and Flacco have combined for 92 regular-season wins, six playoff seasons and one Super Bowl title. But the pressure is on for both to get back to their winning ways. Owner Steve Bisciotti said he considered firing Harbaugh after the Ravens failed to reach the postseason for a third straight year, and Baltimore drafted potential Flacco heir apparent Lamar Jackson in the first round this year. Given that this is already the final season for general manager Ozzie Newsome, the Ravens could undergo a major transformation if they're sitting at home in January again. -- Jamison Hensley
Were the Bengals right to bring back head coach Marvin Lewis?
The Bengals' 0-7 playoff record under Lewis looms large after two non-winning seasons, especially after the team decided in January to bring Lewis back for a 16th and 17th season. The Bengals instead made changes to the rest of the coaching staff and have two new coordinators this year. But if they can't get back to the playoffs in 2018, that decision will be questioned. -- Katherine Terrell
The most fundamental achievement of an NFL team has been lost on the Browns the past two seasons. This team needs to win a game, and it needs to happen as soon as possible. -- Pat McManamon
The defense going from good to great
Ben Roethlisberger in Year 15 is a massive storyline, but the defense will define the season. It struggled late in the year without Ryan Shazier, who must be replaced. Incremental improvements each year haven't resulted in playoff glory. If the Steelers are to add a seventh Super Bowl title, now is the time to make a stand and contain offenses in December and January. Mike Tomlin is betting big on a revised, speed-first attack filled with versatile safeties. -- Jeremy Fowler
Can a healthy Deshaun Watson lead the Texans to the playoffs?
For most teams, success starts and ends with the quarterback, and Houston saw last season the importance of Watson. The Texans' defense is improved, but the additions of Tyrann Mathieu and Aaron Colvin, as well as the returns of J.J. Watt and Whitney Mercilus from injury, won't be enough to be the sole difference in Houston returning to the playoffs. If Watson can stay healthy and play near the level he did in his rookie season, the Texans should be talented enough to make the playoffs for the fourth time in Bill O'Brien's first five years. -- Sarah Barshop
Andrew Luck's health
The quarterback hasn't played in a game since Week 17 of the 2016 season due to a shoulder injury. The Colts are working under the impression that Luck will play this season, which is why they felt comfortable not taking a quarterback in the April draft despite Luck not having thrown a regulation football since October 2017. A healthy Luck will speed up the Colts' rebuilding process because he proved during his first three seasons -- all playoff appearances -- that he's capable of covering up many of the team's flaws.The Colts will be in a tough position if Luck isn't able to regain his form after being out for more than a year. -- Mike Wells
Can the offense and QB Blake Bortles become more consistent?
The offense led the league in rushing but dropped off over the season's final six weeks. The Jags weren't effective rushing in the fourth quarter of the AFC title game, and that is what they want to do: run the ball even when opposing defenses know they want to run it. That's why they signed All-Pro G Andrew Norwell, but it will take more consistency along the offensive line for the running game to be at the level coach Doug Marrone wants. Bortles cut his interceptions (from 16 in 2016 to 13 last year) but needs to bring that total to single digits. He's in the second full season with OC Nathaniel Hackett and says he is more comfortable. That should mean better results. If the offense makes those strides, the Jags should contend for a first-round playoff bye. -- Mike DiRocco
Marcus Mariota in a critical Year 4 under a new offense
There aren't many holes keeping this Titans team from becoming championship contenders, but the big one is maximizing the skill set of Mariota -- who is coming off his worst season as a pro (13 TDs, 15 INTs). Previous head coach Mike Mularkey was fired due to his inability to maximize Mariota. Enter Matt LaFleur, the new, exciting offensive coordinator with the keys to the Titans' offense, who may be even more important than new head coach Mike Vrabel. Mariota's comfort, success and health will determine how far the Titans go in 2018 and the long-term trajectory of this franchise. -- Cameron Wolfe
How Case Keenum plays
Keenum was the centerpiece of the Broncos' offseason and the guy selected to pull the Broncos out of the 5-11 mess of the 2017 season. President of football operations/general manager John Elway said in March that the Broncos picked Keenum over Kirk Cousins in free agency because in his mind Keenum had a better year in 2017 -- 3,547 passing yards and 22 touchdowns after Keenum replaced an injured Sam Bradford in the Minnesota Vikings' lineup. The Broncos' defense should be its usual disruptive self to opposing quarterbacks, so the Broncos' postseason chances will rest largely on three things: (1) how well the Broncos tailor an offense to Keenum, (2) how Keenum builds off his career year, and (3) how well the Broncos solve their ever-thorny offensive line issues. -- Jeff Legwold
The transition to QB Patrick Mahomes
The Chiefs could be confident in winning at least 10 games and making the playoffs with Alex Smith. They did that in four of his five seasons as QB. So if the Chiefs fail this season in either of those endeavors, it's an indictment of their move to Mahomes. Smith had one more season remaining on his contract, so the Chiefs could have waited another year to turn their offense over to Mahomes. -- Adam Teicher
Can the Chargers win the AFC West?
The Bolts return most of their front-line players from a 9-7 team that just missed the playoffs last season. With the rest of the division going through changes at either head coach or the all-important quarterback position, the Chargers have been anointed the favorites to win the AFC West. However, they already lost tight end Hunter Henry for the season with a knee injury and will need to find a way to keep the rest of the team's playmakers healthy to win the division for the first time since 2009. -- Eric D. Williams
Jon Gruden's return
Jon Gruden last coached in the NFL in 2008 and last coached for the Raiders in 2002. Has the NFL passed him by, or did nine years in ESPN's Monday Night Football booth actually make him extremely well-prepared for a return to the sideline -- with his behind-the-scenes access to all 32 teams and voracious appetite for game film? Gruden is now an old-school coach with old-school values -- even if his passion and energy match anything these young players summon. How will his in-your-face personality mesh not only with the younglings, but with a veteran like Marshawn Lynch, who marches to the beat of his own drum? Then there is Derek Carr, who was one of Gruden's top "pupils" on his QB Camp show in 2014. He played at a league-MVP-type level in 2016 but dropped off significantly in 2017. Now healthy, and with the purported QB whisperer that is Gruden in his ear as his coach, how will Carr react? -- Paul Gutierrez
Is Dak Prescott a franchise QB?
There are plenty of storylines -- Jason Garrett's future, a team in transition without Jason Witten and Dez Bryant, Ezekiel Elliott's rebound -- but Prescott tops the list based on the importance of his position. In 2016, he was named the NFL's Offensive Rookie of the Year after leading the Cowboys to a 13-3 record with 23 touchdown passes and four interceptions. In 2017, the Cowboys finished 9-7 and Prescott had 22 TD passes and 13 INTs. The passing game lagged in the second half of last season, with Prescott failing to throw for at least 200 yards in six games. The Cowboys can sign Prescott to an extension after the 2018 season. Should he be paid like a franchise quarterback? If he is more the 2016 version in 2018 and the Cowboys get back to the playoffs, then they have their answer. If he is more middle of the road, they might want to wait on a deal, or they could do one through gritted teeth. -- Todd Archer
Is Eli Manning done?
Or was he a victim of the previous regime's shortcomings? Manning is out of excuses. The Giants added even more weapons and improved the offensive line. This team is going to be as good as the quarterback allows. Manning is looking to bounce back from a pair of disappointing seasons. -- Jordan Raanan
Carson Wentz's comeback
A torn ACL and LCL kept him from being on the field for Super Bowl LII. All eyes will be on Wentz and that left knee to see if he's able to round back into MVP form and lead the Eagles to their second championship in as many seasons. -- Tim McManus
The Alex Smith era begins
And it's an important one because it could well be that the head coach's job security depends on how well Smith performs. Smith is 69-31-1 as a starter since 2011, but, of course, he has received a lot of help. If he continues to win, then Jay Gruden's security will be fine, but if not? Then Gruden will be on a hot seat; the Redskins haven't made the playoffs in two straight seasons and a third consecutive miss would not please owner Dan Snyder. It all starts with Smith, and his performance will help dictate a lot of the Redskins' success. -- John Keim
Will Mitchell Trubisky play well enough for Bears to be NFC North contenders?
Chicago believes it already has a top-10 defense in place, but the Bears' playoff hopes rest on Trubisky's ability to measure up with fellow division quarterbacks Aaron Rodgers, Matthew Stafford and Kirk Cousins. The Bears had one of the NFL's worst scoring offenses in 2017. That must change for Chicago to be relevant in the treacherous NFC North. -- Jeff Dickerson
Is the new regime better than the old one?
The Lions fired Jim Caldwell after back-to-back 9-7 seasons, in part because general manager Bob Quinn thought his team was better than that. He then went out and hired Matt Patricia, the former New England Patriots defensive coordinator, to try to take Detroit from a team always in the middle of the pack to an actual contender. How much difference there is in Year 1 under the Patricia/Quinn leadership duo could tell whether this franchise is on the right path. -- Michael Rothstein
Bye-bye Ted and Dom
For years, Packers fans loved to hate GM Ted Thompson (for his lack of activity in free agency) and defensive coordinator Dom Capers (for underperforming units). New GM Brian Gutekunst has shown early on that he's a tad more aggressive than his old boss, and new defensive coordinator Mike Pettine promises the same. This season should show whether Thompson and Capers were what has held the Packers back from getting to another Super Bowl. If they're not, then perhaps more changes could come next offseason. -- Rob Demovsky
Is Kirk Cousins worth the $84 million the Vikings guaranteed to him in free agency?
Minnesota has been searching for stability at quarterback for more than a decade and believes it secured its next franchise QB this offseason. The investment in Cousins for the next three seasons points to a Super Bowl-or-bust mentality, and given that quarterbacks of Cousins' caliber don't often become available on the open market, Minnesota had to go all-in and move on from the three QBs it had on its roster a year ago. The Vikings are putting a lot of faith into Cousins as the missing piece between this team and a championship, and the last thing the Vikings want to experience is buyer's remorse. Whether Cousins can outperform the quarterbacks he replaced (especially those who are starting on other teams) is the storyline of the Vikings' 2018 season. -- Courtney Cronin
Can the offense regain its 2016 dominance?
The Falcons averaged a league-best 33.8 points per game en route to Super Bowl LI but then dipped to 22.1 points per game last season. The second year under offensive coordinator Steve Sarkisian is expected to be much better, especially with one-time MVP Matt Ryan surrounded by Julio Jones, Devonta Freeman, rookie Calvin Ridley and a host of other offensive weapons. -- Vaughn McClure
Can Norv Turner help Cam Newton return to his 2015 NFL MVP form?
Things will be different for Newton. Turner, the Panthers' new offensive coordinator, is implementing more high-percentage passes and ideally would like Newton to pass more frequently instead of keeping the ball and running himself. With Carolina's defense expected to remain at a top-10 level, how well Newton and the offense perform will determine how far this team goes, because NFC South rivals Atlanta and New Orleans surely will be explosive once again. -- David Newton
Can the Saints' young breakout stars of 2017 lead them to the Super Bowl in 2018?
That's how high expectations are in New Orleans after last year's draft class produced the NFL's Offensive Rookie of the Year in Alvin Kamara, the Defensive Rookie of the Year in Marshon Lattimore and five starters total. The Saints were one play away from the NFC Championship Game last season. They're healthier now and deeper after adding several reinforcements in free agency. And they still have Drew Brees and Sean Payton, making them as legit as any contender in the crowded NFC field. -- Mike Triplett
Can they prove that their 9-7 season two years ago under head coach Dirk Koetter was no fluke?
Was hanging on to Koetter and the rest of the coaching staff after they fell to 5-11 last season the right call? Previous Bucs coaching staffs under Greg Schiano and Lovie Smith weren't afforded the luxury of a third year, but neither of those teams had the benefit of a winning season in Year 1. -- Jenna Laine
Sam Bradford's health
When he's healthy, Bradford is one of the most efficient quarterbacks in the NFL, but his injury history doesn't suggest he'll stay healthy for long. As Bradford's health goes, so go the Cardinals. If he stays on the field, the Cardinals could see their first winning season since 2015. If he doesn't, Arizona may be in for a third straight year of .500 or worse. And whether Josh Rosen, Arizona's first-round pick, plays this season could also depend on whether Bradford gets hurt. -- Josh Weinfuss
For the 2017 Rams under first-year coach Sean McVay, the bar was low -- they simply needed to improve on the previous four-win season. After winning 11 games, finishing atop the NFC West and making their first playoff appearance in 12 years -- not to mention acquiring All-Pro cornerbacks Aqib Talib and Marcus Peters and All-Pro defensive lineman Ndamukong Suh this offseason -- the 2018 Rams are early favorites to again win the division and make a playoff run. Can they perform under the pressure of higher expectations? -- Lindsey Thiry
Will Jimmy Garoppolo seize the opportunity?
For the Niners, this season is all about Garoppolo and his first opportunity to be a starter for an entire season. Garoppolo has heard the questions about his performance based on a small sample size, and now he's getting the chance to prove he can be the franchise quarterback the 49ers believe he can be. With question marks at all levels of the defense, the Niners' chances to become playoff contenders amid higher expectations will come down to whether Garoppolo can deliver on his immense promise. -- Nick Wagoner
Seahawks' defense in transition
Technically, two of the founding members of the Legion of Boom are still with the team. But Earl Thomas is entering the last year of his contract, with no indication that an extension is coming anytime soon, and Kam Chancellor may never play again because of a neck injury. Richard Sherman is gone, as are two other longtime stalwarts in Michael Bennett and Cliff Avril. What has been a historically excellent defense driven by its secondary will now revolve around linebackers Bobby Wagner and K.J. Wright. And after losing so many key pieces on that side of the ball, Pete Carroll's team needs another wave of stars to emerge. Cornerback Shaquill Griffin and defensive end Frank Clark are two possibilities. -- Brady Henderson