USA TODAY Sports' Lorenzo Reyes ranks and discusses the best offensive units in football.
NFL rosters are essentially set until training camps open later this month. In the meantime, USA TODAY Sports has analyzed each team's depth chart and is ranking units throughout the league before providing an overall hierarchy of talent.
Today's positional group: Running backs
1. Dallas Cowboys: Ezekiel Elliott rumbled to 1,631 yards and the rushing crown as a rookie even while taking a seat in Week 17. With a year's experience operating behind the NFL's premier line and continued improvement from QB Dak Prescott, Elliott should only get better — and 2,000 yards isn't out of the question. However if he's forced to miss time amid an ongoing league investigation into his behavior or for injury, Dallas has very capable veterans, Darren McFadden and Alfred Morris, in reserve.
2. Pittsburgh Steelers: There's no better all-around back in the league than Le'Veon Bell, who last year became the first player to average 100 yards rushing and 50 receiving in the same season. With his patient running style and exquisite route running, Bell is certainly capable of being the second player to rack up 2,500 yards from scrimmage and could challenge Chris Johnson's record (2,509). But the Steelers are toast if Bell goes down again. Rookie James Conner could start his career as a nice goal-line banger.
3. Arizona Cardinals: Only a Week 17 injury prevented David Johnson from becoming the first player to have 100 yards from scrimmage in all 16 regular-season games. Now he's set his sights on becoming the third player to have both 1,000 yards rushing and receiving in the same year. Don't bet against him ... but don't bet on the Cards if gets hurt.
4. Atlanta Falcons: Devonta Freeman and Tevin Coleman parlayed their Mr. Inside/Mr. Outside roles into nearly 2,500 combined yards and 5.8 yards per touch. Good luck finding a better complementary duo.
5. Tennessee Titans: DeMarco Murray and rookie Derrick Henry were a thunder and thunder combo, combining for nearly 2,300 scrimmage yards for the NFL's third-ranked rushing offense. Behind an elite offensive line and ever-improving QB Marcus Mariota, don't expect any drop-off.
6. Oakland Raiders: They've got a road-grading line and balanced attack. As rookies, Jalen Richard and DeAndre Washington combined for nearly 1,000 yards by averaging 5.6 yards per carry. But the excitement here is all about Marshawn Lynch's homecoming. Though his offseason buzz has been superb, he must show he's refreshed and hasn't collected rust after a year off.
7. New Orleans Saints: This could be fun to watch. Defenses will surely be reluctant to load the box against QB Drew Brees. Yet if they don't, a steady diet of rejuvenated Adrian Peterson, hungry Mark Ingram and versatile rookie Alvin Kamara awaits. Peterson may go off in a bid to disprove the naysayers and ageists.
8. Miami Dolphins: Jay Ajayi burst onto the scene in 2016 with a trio of 200-yard efforts. His next challenge will be consistency given he was held below 100 yards in 11 of his 12 other appearances last season. After averaging 5.4 yards per carry as a rookie, Kenyan Drake might deserve more touches.
9. Buffalo Bills: No team rushed for more yards in 2016, though more than 1,100 came courtesy of QB Tyrod Taylor and since-departed RB Mike Gillislee. Expect Buffalo to remain committed to the run ... as long as 29-year-old LeSean McCoy can keep it going.
10. Chicago Bears: After finishing second in the league with 1,313 rushing yards as a rookie, no one will sleep on Jordan Howard in 2017. He does need polish as a receiver.
11. Los Angeles Chargers: Melvin Gordon put his rookie struggles way behind him. Only hip and knee problems at the end of year prevented him from his first 1,000-yard effort. More importantly to the Bolts, he scored 12 times in 13 games after being shut out in 2015.
12. Seattle Seahawks: Eddie Lacy, Thomas Rawls and C.J. Prosise, initially a wideout at Notre Dame, all bring something to the table. That's why this figures to be a committee as long as they all remain relatively healthy — which could be an issue if the O-line continues to hinder their efforts.
13. Jacksonville Jaguars: They're hoping for an Ezekiel Elliott-esque impact from rookie Leonard Fournette, who enters the league saddled with unfair comparisons to Adrian Peterson. But the Jags hope to parlay Fournette's punishing running style into a more physical and balanced offense designed to be less reliant on struggling QB Blake Bortles.
14. Los Angeles Rams: Todd Gurley's demise was one of the shocking subplots of 2016. He seems confident new coach Sean McVay's offense can again unleash his talent, but Gurley also needs QB Jared Goff to perform far better if he's going to get out of neutral.
15. Philadelphia Eagles: After running for a league-best 18 TDs in New England last year, LeGarrette Blount projects as the new workhorse here. But he's never caught more than 15 balls in a season, so Darren Sproles and wispy rookie Donnel Pumphrey figure to get the nod on passing downs.
16. Carolina Panthers: Jonathan Stewart is a punishing runner, but his physical style also seems to backfire from a durability perspective. With his Velcro hands and quicksilver feet, Christian McCaffrey should create major defensive headaches as a receiver. But he also ran quite well between the tackles at Stanford.
17. Cincinnati Bengals: With Jeremy Hill's contract expiring after the season, and Gio Bernard coming off knee reconstruction, it only seems a matter of time before controversial but talented second rounder Joe Mixon is the leading man. He could be a significant upgrade provided his red flags don't resurface.
18. Baltimore Ravens: If Terrance West is in the game, Baltimore will likely be running. When Danny Woodhead enters, the Ravens will likely throw — and Woodhead could snare 75 balls. Slightly predictable but not necessarily ineffective. Kenneth Dixon will join the fray following a four-game suspension.
WATCH: Five players who need to step up
USA TODAY Sports NFL reporter Lorenzo Reyes looks at the five players who need to take their games to another level if their teams are going to have a shot at making the playoffs this season.
19. Minnesota Vikings: With Adrian Peterson injured and the line in shambles, they ranked dead last running the ball last year. There are new faces up front now, and Peterson has been replaced by veteran Latavius Murray and highly regarded rookie Dalvin Cook, who seems likely to inherit the bulk of the work.
20. Kansas City Chiefs: Rookie Kareem Hunt will take touches away from Spencer Ware and Charcandrick West. All told, expect a productive, if undynamic, approach that keeps the chains moving.
21. New York Jets: As bad as the team was in 2016 and projects to be this year, it's got a pair of highly capable backs in Matt Forte and Bilal Powell. Both eclipsed 1,000 yards from scrimmage last season despite the issues and injuries around them.
22. Washington Redskins: They plan to go with the hot hand after ranking 21st in 2016. Rob Kelley will likely see most of the touches on early downs with Chris Thompson subbing on passing downs. But don't sleep on rookie Samaje Perine, a physical runner who could make a big impression.
23. Houston Texans: Lamar Miller wasn't the game breaker Houston was hoping for, but he kept an offense that struggled to pass moving on the way to a division crown. With better balance, he's capable of more quick-strike plays.
24. New England Patriots: It must be assumed Bill Belichick knows what he's doing. He's definitely got a fresh challenge after letting LeGarrette Blount, who produced 62% of the team's rushing output in 2016, move on. This year's committee includes Dion Lewis, newcomers Mike Gillislee and Rex Burkhead and Super Bowl hero James White. But don't be surprised if QB Tom Brady spends a lot more time chucking it than handing off.
25. Green Bay Packers: They're confident converted wideout Ty Montgomery is the answer after he averaged nearly 6 yards per rush in limited duty last year. But if he falters, rookie Jamaal Williams could get his shot.
26. Tampa Bay Buccaneers: Doug Martin let the Bucs down on and off the field and begins this season with a three-game suspension. Charles Sims, Jacquizz Rodgers and rookie Jeremy McNichols should all have the opportunity to shine this September against defenses stressed by the Tampa air game.
WATCH: Five fiercest training camp battles
USA TODAY Sports' Lorenzo Reyes says that these five position battles will be the most exciting to watch throughout NFL training camps.
27. Denver Broncos: With OC Mike McCoy back and the O-line apparently better, the ground game should get back on track. And it needs to for the sake of whichever young quarterback wins the job this season. C.J. Anderson and Jamaal Charles hope their knee issues are behind them, while Devontae Booker hopes his rookie year is behind him.
28. Cleveland Browns: Despite their offensive shortcomings, the Browns somehow managed 4.9 yards per rush in 2016, second in the league. Now they've upgraded the offensive line. Isaiah Crowell and Duke Johnson could be fantasy sleepers.
29. San Francisco 49ers: Carlos Hyde could use good health and a robust stat line as he plays for a new contract. But he could have to stave off a challenge from rookie Joe Williams while learning an entirely new playbook.
30. Detroit Lions: They didn't have anyone reach 400 yards last year. But the Lions hope improved blocking and a healthy Ameer Abdullah change their fortunes.
31. Indianapolis Colts: Frank Gore methodically strung together a 1,000-yard season, 3.9 yards at a pop, at age 33. At 34, he'd probably welcome more help from Robert Turbin, who's impressed this offseason.
32. New York Giants: Not getting the job done. Still. The Giants haven't had a 1,000-yard rusher since 2012. Paul Perkins is the latest candidate hoping to change that for a team that produced just 3.5 yards per rush in 2016 and a league-low six rushing TDs.
Follow Nate Davis on Twitter @ByNateDavis
PHOTOS: NFL players with great names