Darren McFadden, most recently the third-string running back for the Dallas Cowboys, quietly retired from football a few days ago, announcing his departure in a tweet three days after being waived. McFadden spent 10 mostly lackluster years in the NFL, hampered by injury and a lengthy tenure with the then-talentless Oakland Raiders. By contrast, his college career stands as one of the greatest of recent decades. A phenom at the University of Arkansas, the two-time Doak Walker Award winner and two-time Heisman Trophy runner-up was the centerpiece of the Razorbacks’ wildcat offense—the “wild hog,” in Arkansan parlance. McFadden was the spark for an offensive innovation that set the sport ablaze, and, for a brief period in the 2000s, looked like it could be the future of football. Defenses eventually figured out the wildcat, and the formation’s rise and fall might sign like a historical oddity. But the fad McFadden spawned left a powerful mark on the game.

In football today, the skill positions as we once knew them are largely extinct, and the game is dominated by a class of hybrid superathletes capable of fulfilling virtually any role on the field at a given time. “In the pro game, we’re seeing it more and more,” wrote the Ringer’s Danny Kelly last year, “running backs playing the roles of receivers.

Receivers motioning into the backfield to run the rock. Quarterbacks racing for yardage. Runners lining up under center. Classically defined ‘positions’ are increasingly meaningless in the NFL.” As the spread offenses and nickel defenses of the college game have migrated into the NFL, the league has increasingly come to value fast, versatile athletes whose positional roles are difficult to define: mobile quarterbacks such as the Seahawks’ Russell Wilson and Cam Newton, pass-catching tailbacks like the Falcons’ Devonta Freeman and Tevin Coleman* and the Saints’ Alvin Kamara, and even the Browns’ two-way rookie Jabrill Peppers.

While talk of “positionless football” is now all the rage, 15 years ago it was an unnamed concept getting tested out in the laboratories of high school football. Back then, Gus Malzahn was the head coach at Springdale High School in Arkansas. Malzahn, a key figure in the development of the shotgun spread offense, also played a major role in reinventing Pop Warner’s old single-wing offense. The wildcat, very simply, is a single-wing–ish formation in which a strong runner (typically a running back) plays the traditional quarterback position, and has the option of running, handing the ball off, or throwing. With the spread as his base and the wildcat as a changeup weapon, Malzahn took Springdale to an Arkansas state championship in 2005, a season in which this team outscored opponents 664-118.

It’s unfair to dismiss the wildcat as a gimmick that no longer works.

Malzahn brought the wildcat with him to the University of Arkansas, becoming the school’s offensive coordinator in advance of the 2006 season. The team immediately vaulted into SEC title contention, and its everything-old-is-new-again formation made its way into playbooks across the country. A Wall Street Journal article from 2009 season said 80 percent of high school and college teams were expected to feature the formation that year. The NFL, too, bought into the craze, with the Miami Dolphins and Ronnie Brown using it to light up the vaunted New England Patriots defense for 38 points in 2008. In that game, the Dolphins ran the wildcat six times for 118 yards and four touchdowns, ending the Pats’ 21-game regular-season win streak and heralding the wildcat as a revolutionary offensive tool. “An inspired bit of football poetry,” the Journal called it, “affirming as it does that there are still an infinite number of new ways to re-imagine inherently finite spaces.”

While high school, college, and pro teams copied Malzahn’s wildcat, no one deployed it with the same sustained success as the 2006 and 2007 Arkansas Razorbacks. (Malzahn left Arkansas for Tulsa before the 2007 season, but his old team continued to run the wildcat in his absence.) Those Arkansas backfields featured future Madden cover boy Peyton Hillis and future first-round draft pick Felix Jones. They also had the nation’s best college football player. McFadden’s de facto command of the Arkansas offense became absolute when he lined up at quarterback, posing a triple-threat to hand the ball to Jones, run it himself, or chuck it. His length and upright running style drew comparisons to Eric Dickerson, while his arm inspired joking that he could throw the ball better than his conference rival Tim Tebow.

While then–Arkansas head coach Houston Nutt expressed concern that McFadden might not be able to manage the play clock and snap count in high-stakes situations, McFadden proved him wrong. In the 2006 SEC Championship Game between Arkansas and Florida, McFadden—lining up in the wildcat on the Florida 2-yard line—made brief, meaningful eye contact with Jones, who was lined up as a slot receiver. An instant after the snap, the “running back” fired a touchdown pass to Jones without a moment’s hesitation. This play was drawn up as a run. The offensive linemen blocked for a run. Only McFadden and Jones, thanks to a wordless nod at the line of scrimmage, knew where the play was going. This is the sort of creativity, whimsy, and confidence that it takes for a running back to take over the quarterback position. Without a player of these qualities—without a player like McFadden—the wildcat never would have taken off, and taken over the football world.

McFadden also threw an interception in that 2016 SEC title game.

(Nobody’s perfect.) In the NFL, he rarely got the chance to test the offensive scheme that made him famous. The Dolphins’ experiment with the formation eventually fizzled out, and, by 2010, it looked more like a fad than a revolutionary innovation. In a recent SB Nation tribute to the formation, Alex Kirshner wrote that when the wildcat rears its head today, it serves mostly as “an indicator that a team has run out of ideas.”

While the formation is no longer the craze it once was, it’s unfair to dismiss it as a gimmick that no longer works. Auburn, where Malzahn is now the head coach, ran the wildcat extensively on its way to this year’s SEC title game. And the formation still has a place in the NFL: Last week, Falcons wide receiver Mohamed Sanu threw a 60-yard touchdown pass from the wildcat, and the Buffalo Bills and Minnesota Vikings used it frequently last season.

The wildcat’s influence on the sport is broader still. Kirshner points to the wildcat as a precursor to today’s run-pass options, in which a quarterback can use his legs or arm depending on what the defense gives him. In 2011, Deadspin’s Barry Petchesky took a similar stance, arguing that “the rise of the hybrid player is the spiritual descendant of the Wildcat craze.” It was McFadden’s multipositional versatility that stretched the boundaries of a stodgy sport. The wildcat did not achieve the ubiquity it looked like it might in 2008. It nevertheless changed the sport forever.

McFadden ran for 5,421 yards in the NFL, scored 28 touchdowns on the ground, and caught five more. (He also threw for one, in 2013.) But the magnum opus of his career came against LSU on Thanksgiving weekend in 2007. On that day in Baton Rouge, Arkansas pulled off a thrilling triple-overtime upset over the No. 1 Tigers in which McFadden ran for three touchdowns and passed for another. In the third quarter, he ran for a 73-yard touchdown from the wildcat, a play that, bizarrely, featured a touchdown-sustaining block by Arkansas quarterback Casey Dick. Before cutting to commercial, CBS ran a highlight of the play that finished with a close-up of McFadden standing alone in LSU’s end zone, looking defiantly into America’s living rooms. “College football is changing every week,” said announcer Gary Danielson, “the wild hog works again.” You can see those changes on the field today, and you’ll see them decades from now. Those changes are Darren McFadden’s legacy.

*Correction, Dec. 3, 2017: This post originally misspelled Tevin Coleman’s first name.