The 2016 Falcons offense was one of the most efficient units the NFL has ever seen, leading the league in scoring (33.8 points per game) and Football Outsiders’ offensive DVOA. What made it all the more impressive is that no one predicted its success. Atlanta averaged 21.2 points per game in the 2015 season, 21st in football. The Falcons enjoyed a solid start to that campaign before cratering down the stretch, and those early flashes of upside hardly hinted at what was to come.

Atlanta’s gigantic leap was made possible by a confluence of small factors that included signing center Alex Mack, lucking into speedy receiver Taylor Gabriel, and benefiting from quarterback Matt Ryan growing increasingly comfortable in his second year with coordinator Kyle Shanahan. Combined, those elements were enough to take a unit mired in the middle of the pack and turn it into the league’s best.

As the offseason begins, now is a good time to identify a few units that could make a similar rise with the right combination of moves over the next few months.

The Eagles Defense

Of all the groups on this list, Philadelphia’s defense has the smallest jump to make to become the league’s top unit next season. The Eagles allowed 20.7 points per game during the 2016 campaign (12th best in the NFL), and that undersells how well they performed according to other metrics. Coordinator Jim Schwartz’s group finished fourth in defensive DVOA, behind only the Broncos, Giants, and Cardinals. That disparity between traditional and advanced stats happened in part because Philadelphia faced a tougher slate of offenses than any other team in football: With four combined games against Washington and Dallas in addition to matchups with Atlanta, Pittsburgh, and Green Bay, the Eagles played nearly half of their games against teams ranked in the top 10 of offensive DVOA.

The Eagles’ decision to bring in Schwartz in January 2016 had some (read: me) salivating over the idea of edge rusher Brandon Graham and interior force Fletcher Cox playing in the attacking system that made the Bills defense so stifling under Schwartz in 2014. For the most part, that shook out. Cox didn’t explode in quite the way I’d imagined, but both he and Graham had great seasons and played significant roles in making Philly’s front four the foundation of its success.

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Most of that group will return this fall. Nose tackle Bennie Logan is set to become a free agent who will probably be too expensive for the Eagles to retain, especially after the franchise handed a market-setting deal to Cox and a sizable contract to defensive end Vinny Curry last offseason. But in Cox, Graham, Curry, two very good linebackers (Jordan Hicks and Nigel Bradham), and a complementary pair of safeties (Rodney McLeod and Malcolm Jenkins), Philly has a rock-solid core of defenders — particularly through the middle — that stacks up with any in the league.

What held the Eagles back last season were their problems on the outside. Only five teams gave up more passes of 20-plus yards (57), and a disproportionate amount of that damage came down the sidelines. Philly has become a cornerback wasteland, to the point that one of the team’s starters from last year, Leodis McKelvin, already has been released. Trading Eric Rowe to New England last September for a fourth-round pick in next year’s draft certainly didn’t help matters. Still, no matter how they got here, the Eagles have some serious work to do at the position this offseason.

There will be some options when the free-agent market opens next month. Philadelphia has only about $10 million in cap room, which likely will keep it out of the running for corners like A.J. Bouye, Stephon Gilmore, and Trumaine Johnson at the top of the market. But even guys a little further down the list — like slot man Logan Ryan or Prince Amukamara — would provide a roster upgrade. The Eagles already have a talented defense; their goal this offseason should be to make incremental improvements that can help prevent the type of backbreaking plays that render that talent moot.

The Dolphins Offense

Miami has some pressing personnel questions to answer in the next month or so, but with head coach Adam Gase and an offense that has the chance to keep all of its key pieces, the Dolphins are closer to breaking through than many people may think.

The front-office duo of Mike Tannenbaum and Chris Grier should make it a priority to retain downfield threat Kenny Stills, who bounced back from his disappointing 2015 season in a big way last fall: He made 42 catches for 726 yards and a team-high nine receiving touchdowns. Bringing back Stills would allow the Dolphins to move forward with a skill-position group that has the potential to be pretty damn good. The combination of Stills, Jarvis Landry, DeVante Parker, and tailback Jay Ajayi had plenty of moments last season, and each is 24 or younger. Tight end is another area of concern for Miami (both Jordan Cameron and Dion Sims are set to hit free agency), but finding that answer should take a backseat to some other offseason needs.

Few teams in the league had more resources tied up in their offensive line than the Dolphins last season, who spent three recent first-round picks on linemen and had a tackle (Branden Albert) making $8.4 million. The problem is that unlike the Cowboys, Raiders, and Titans, Miami didn’t get enviable returns on investment. Part of its issue was losing center Mike Pouncey to a hip injury for 11 games last year. He’ll be back this fall, but the same can’t be said about the 32-year-old Albert, who’s coming off a rough season (one that was marred by a wrist injury, just the latest in the litany of injury issues he’s had in Miami). The Dolphins released him on Thursday, saving about $7.2 million.

After cutting ties with the former big-money free agent, Miami has about $48 million in cap space without making any other moves. That leaves it with plenty of cash to re-sign Stills and help fill out the line. The logical move to replace Albert would be to slide 2016 first-round pick Laremy Tunsil to tackle (example no. 1,281 of why drafting the best available player isn’t a bad idea). That’d leave holes at both guard spots, but this free-agent class happens to be loaded with interior offensive linemen. Guys like T.J. Lang, Ron Leary, Kevin Zeitler, and Larry Warford are all available, and each would represent a massive upgrade for Miami.

Getting steadier play out of the guys up front would be pivotal, as the rest of the Dolphins offense is headed in the right direction. Quarterback Ryan Tannehill seemed to settle in during his first season under Gase (save for a rough day against the Ravens in December) before going down with a knee injury, and the continuity that would come with another year in the offense could be enough to help him — and this unit — take a significant step forward. If Pouncey fully recovers and some tweaks elsewhere are made, Miami (which finished 14th in offensive DVOA) could be dangerous.

The Bears Defense

Wait, hear me out! The Bears finished 22nd in defensive DVOA and 24th in scoring defense (24.9 points per game) last season, but considering the number of injuries they had to deal with, those figures should serve as a reminder that coordinator Vic Fangio is one of the best in the business.

Inside linebacker and 2016 free-agent prize Danny Trevathan missed seven games with knee and thumb injuries. Edge rusher Pernell McPhee missed just as many, and even when he was on the field, the knee injury that put him on the PUP list to start the season was a consistent issue. Nose tackle Eddie Goldman was out for 10 games with a litany of lower-body ailments. And cornerback Kyle Fuller didn’t play a snap because of a knee problem.

The 2016 Bears were a mess, and they still managed to avoid falling into the bottom tier of NFL defenses. Looking at their preliminary 2017 depth chart should be enough to give fans hope. With Trevathan, McPhee, Goldman, 2016 standout Akiem Hicks, promising young pass rusher Leonard Floyd (seven sacks as a rookie), and a few other pieces, Chicago has the makings of a startlingly good front seven.

The secondary is where the Bears desperately need an influx of talent, and with the crop of cornerbacks available and the franchise’s reservoir of cash, they’ll have the means to acquire it. General manager Ryan Pace is working with about $51.6 million in cap room, and that’s before the expected release of quarterback Jay Cutler provides an extra $14 million in space. Even if the Bears choose to bring back top receiver Alshon Jeffery, that’s a silly amount of cash with which to work. Any of the premier corners set to hit the market (Bouye, Gilmore, and Johnson) could be in play. Pair some defensive back help with Fangio and a front seven that could be excellent (when healthy), and Chicago is a candidate to stun some people next season.

The Titans Offense

The accomplishments of the 2016 Titans — who showed flashes of excellence when many thought they would be a train wreck — are more surprising than any leap the team could make this offseason. Tennessee finished ninth in offensive DVOA (up from 32nd in 2015) and 14th in points per game (23.8), and every crucial piece from its unit should be back next fall.

That out-of-nowhere improvement was made possible thanks largely to the offensive line, which was great in its first season together. Center Ben Jones isn’t quite the player Mack is in Atlanta, but his addition provided the same type of stabilizing impact. The Titans have to decide if they want to roll with career backup Josh Kline (who filled in for an injured Chance Warmack beginning in Week 3) and prioritize continuity up front, but in any case, this group should be the strength of the offense.

Along with hoping that quarterback Marcus Mariota can take another step forward in his third NFL season (think about what Derek Carr did in 2016), the Titans could use help at receiver. A team with Rishard Matthews as its primary option on the outside has some self-reflecting to do. Tennessee has a ton of cap space to work with (about $62 million) and could pursue any of the wideouts available in free agency. Names like Jeffery and Terrelle Pryor will probably be discussed, and one especially intriguing option is DeSean Jackson. Tennessee enjoys taking its shots (only Cam Newton and Jameis Winston averaged more air yards per attempt than Mariota last season), and Jackson would be able to provide that element at a cheaper price than the top receivers on the market.

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The Rams Defense

Including the Rams here is more about faith in new defensive coordinator Wade Phillips than anything else. From a personnel standpoint, they’re actually in worse shape than they look on the surface. Extensions for Mark Barron, Michael Brockers, and Tavon Austin (his cap figure, about $15 million, hurts even to look at) have left them with about $37 million in cap space and some big names set to hit free agency.

Both cornerback Johnson and safety T.J. McDonald are about to reach the open market; if the Rams can find a way to re-sign them, that would go a long way toward giving Phillips a chance to work his magic. While much has been made of the schematic change Los Angeles will undergo in the coming months, any worries that Phillips’s hiring will detract from the team’s talent up front are overblown. Phillips runs an attacking, one-gap defense that lets his penetrators go to work. Even with issues elsewhere on the roster, the Rams will still line up defensive tackle Aaron Donald as a three-technique and watch him ruin the world. The hope is that defensive end Robert Quinn will stay healthy enough (he’s missed 17 combined games over the past two seasons) to make the type of impact he’s had in the past.

The Rams finished 15th in defensive DVOA last season, and will enter the 2017 campaign with Quinn, Donald, William Hayes, Dominique Easley, and the pieces to form a dominant pass rush. If they can retain enough of their secondary to give Phillips a group that’s workable on the back end, there’s enough here for this unit to cause some serious problems.