Last year, the Cowboys were bad. They eked out four wins, finished 27th in DVOA, and ended the season in the NFC East’s cellar.

Despite Dallas’s overall struggles, its run game remained very good. The Cowboys finished sixth in the NFL in yards per attempt (4.6) on the year, ninth in rush yards per game (118.1), sixth in Football Outsiders’ adjusted line yards, and ninth in rush DVOA.

They did that without 2014 rushing champion DeMarco Murray, who left for Philly in free agency, and they did it without Tony Romo for much of the year (he missed 12 games). Opposing defenses could take the field secure in the knowledge that the Cowboys couldn’t throw the ball against a team of tackling dummies, but Dallas still produced in volume and efficiency. And it all came down to having the best offensive line in the NFL, a group so good it made oft-injured veteran Darren McFadden — who hadn’t exceeded 3.4 yards per carry the previous three seasons — look like a star again. The former Raider averaged 4.6 yards per carry (2.3 of those yards coming before contact, third most in the NFL) and finished fourth in the league in rushing with 1,089 yards.

Dallas returns all five of its starters on the line in 2016, and three of them are All-Pros that the Cowboys took in the first round: tackle Tyron Smith (ninth overall in 2011), center Travis Frederick (31st in 2013), and guard Zack Martin (16th in 2014). Building a punishing running game is part of a clear plan, which Dallas doubled down on by taking Ohio State’s talented and dynamic running back Ezekiel Elliott fourth overall in this past spring’s draft. (Elliott’s ex-girlfriend has accused him of committing domestic violence; he denies the accusations.) At its core, this team wants to run over its opponents and control the clock with a demoralizing, physical rushing attack.

Foundationally, the Cowboys utilize the zone blocking scheme up front, with 58 percent of their runs coming behind that style of blocking, per Pro Football Focus. It’s a system that was popularized in the 1980s, but perfected by Alex Gibbs and the Broncos in the ’90s. Gibbs, the godfather of the scheme, helped make the Broncos Super Bowl champions in 1998 and 1999, and running back Terrell Davis was a league MVP and three-time All Pro while operating almost exclusively in that system.

These runs, against the Giants and Seahawks, show you how Dallas mixed up wide and tight zone runs effectively in 2015. The idea on wide zone is to flow laterally up front, stretching the defense out while creating cutback lanes upfield.

When defenses start cheating to try to keep the running back from getting wide in the first place, the Cowboys simply change it up and run the tight zone.

Gibbs, however, wouldn’t approve of how often the Cowboys go away from this base system.

“I do not pull anybody at any time,” Gibbs said at a coaching clinic in 2007. “I do not want to run any plays that pull linemen. They are good plays, but not for me. I want to run zone, and that is what my players know how to run. We run zone wide and tight, and that is it. If you want to run something else, do not call me and ask for help.”

Purveyors of the zone blocking scheme, and particularly those on the Gibbs coaching tree, typically remain faithful to that ideology. Gary Kubiak, the offensive coordinator and quarterbacks coach on those Broncos Super Bowl teams in ’98 and ’99, ran zone in Denver 85 percent of the time last year, per PFF tracking, and the Ravens, who carried Kubiak’s ZBS over under new offensive coordinator Marc Trestman, ran zone concepts on 89 percent of their run plays. Tom Cable, who learned the system under Gibbs in Atlanta, had his Seahawks run zone about 85 percent of the time.

Dallas coach Jason Garrett and offensive coordinator Scott Linehan, together with offensive line coach Frank Pollack (who coached under Gibbs in Houston in 2008 and 2009), see things differently. Although they are widely considered a zone blocking team, their rare collection of blue-chip talent on the line has allowed them to design a ground game that maximizes the valuable assets they’ve invested in over the past five years. It means the Cowboys’ playbook is varied and creative. And, much to Gibbs’s chagrin, it means they frequently pull linemen.

Here are some of the schemes that Dallas has added to its repertoire.

Power-O

With the play-side tackle (and tight ends) down-blocking on the defensive end (and linebackers), running power means you’re pulling a guard (or multiple offensive linemen) behind them as a lead blocker. Here, against the Jets in Week 15, La’el Collins pulls to his left to smash into the unblocked (by design) outside linebacker. McFadden’s job is to follow Collins and either cut inside if Collins “kicks out” the linebacker (seals him to the outside) or bounce it outside if the linebacker tries to cheat inside. Against New York, he bounced and picked up big yardage.

You can do the same thing with your center (and guard), too.

The Counter

The counter looks a lot like a zone run for the first step or two as well, but then busts out the back side of where the defense thinks the play is going. Here, in this play from Week 11, you can see both Dolphins linebackers react to McFadden’s first step left. McFadden then reverses direction and follows the lead blocks of his pulling guards to the right.

The Toss Sweep

On the toss sweep, you see the tight end and receivers cracking back into the formation, blocking pursuing defenders, as the offensive tackle pulls around the crack-backs and leads the way for the running back. With someone as fast as Smith as your left tackle, you can do some fun things. Against Washington in Week 17, he runs all the way down the damn field. It’s rare to see that kind of athleticism from an offensive lineman, and Dallas takes full advantage of Smith’s ability — even if the running back fumbles before going into the end zone.

Good Old Man-to-Man

Sometimes, you just block the guy in front of you. Against the Bills in Week 16, McFadden runs straight ahead first — what’s called “pressing the line” — and that makes defenders commit and fill their gaps instead of flowing laterally first. Once he’s duped the linebackers into coming forward, he cuts outside and finds a nice gap to cut through off of his tight ends’ blocks.

The Cowboys’ versatility makes them very hard to game plan for (you have to prepare for a lot of different looks), and even harder to predict (their different looks play off of opponents’ in-game adjustments). By adding a talent like Elliott to the backfield, the pieces are in place in 2016 for a big jump back to being an elite rushing attack. Having Tony Romo and a real passing game in place will only make the Cowboys run game that much more dangerous. And even if the oft-injured Romo gets hurt again this year, Dallas can always look to its athletic backup and preseason darling, Dak Prescott, to add another element to the run game with designed quarterback runs and the read option.

Most teams will dedicate all their time to mastering one system, and if they’re lucky, they’ll get good at it in time. The Cowboys have the unique ability to run such a wide range of plays because they’re so damn good in their core concepts. With Dallas, running zone is just the beginning.