Perhaps no league has seen as much change over the past two decades as the National Football League (NFL).

Running backs were once franchise cornerstones, but now they cycle through as fast as the Madden video game updates. Defenses used to feature constant, collapsed formations like the 46 to beat up offenses and force them to get physical. Now, with few exceptions, speed-oriented and spread-out defenses reign supreme. Tight ends used to be a sixth offensive line position 80 percent of the time. Now guys like Jimmy Graham and Rob Gronkowski don’t even consider lining up with the big fellas up front.

But what might be the greatest shift of all is the impetus on coaches having a major say over their players and roster-related decisions. Yes, the era of the NFL back office, with decision-making general managers (GMs), may be winding to an unceremonious close.

More often than ever we are seeing coaches hand-pick their own GMs—executives with similar system theories to the coaches who hire them. Instead of the old days where the owner hired the GM, who hired the coach, who coached the GM’s players—now we have many owners hiring the coach who takes care of every non-business-related aspect of the organization.

Talk about flipping the system upside down.

Football is simply a more complex game now. The game-planning improves every day, the style of play is evolving, and the science behind scouting players and teams is light-years ahead of past standards. With these trends come innovative, varied, and diligent coaches who insist on their own strategies—and work to foster their beliefs into every part of the teams they coach. This is why the GM position is slowly dropping below the head coach position on the NFL totem pole.

Coaches Bill Belichick of the New England Patriots, Andy Reid of the Philadelphia Eagles and Kansas City Chiefs, Mike Tomlin of the Pittsburgh Steelers, and Pete Carroll of the Seattle Seahawks have all had great success and have either hired their own GM or have had equal say on team decisions with their respective GM.

John Schneider, Seattle’s GM, is a tremendous example of a GM who saw the warning signs beyond the horizon. In 2009, he backed up the money truck and dumped millions on Carroll to lure him from college football because Carroll was a coach who had a similar—almost identical—football philosophy to Schneider. How has that turned out? Well, I think to say “good” would be the understatement of the week.

This GM-coach issue has come to the forefront recently thanks to absolute discord in San Francisco and Philadelphia. Neither situation was pretty—and both came out on opposite ends when all was said and done.

In San Francisco, GM Trent Baalke hired Coach Jim Harbaugh away from college football in 2011. It was Baalke’s first days in the GM seat—and Harbaugh was a huge score. From a roster-building perspective, Baalke had no prior GM experience and the 49ers franchise he had been a part of since 2005 had been dismal to say the least.

Harbaugh came in and turned around the 49ers faster than anyone imagined, taking the team to three NFC Championship games and a Super Bowl in his first three seasons. All the while, controversy grew behind the scenes. The inexperienced Baalke had absolute strategic differences with Harbaugh—and Harbaugh’s dogged personality was winning decision battles behind the scenes strictly out of steadfast-stubbornness. But Harbaugh had a reason to be stubborn—he was the independent variable of the 49ers turnaround. Not an executive in football could nor would deny that Harbaugh should earn the praise for the new era in San Francisco.

Baalke obviously didn’t like this. As Harbaugh headed into the final year of his contract in 2014, the despondent GM didn’t give him an extension—and Harbaugh coached out his final year (which was his worst) as a lame duck.

What happened after?

Harbaugh bolted back to college football and Baalke searched around aimlessly for a coach before hiring the 49ers’ own defensive line coach, Jim Tomsula—a man who had never been a coordinator, let alone a head coach. What did the rest of Harbaugh’s highly-respected staff think of that? Well, not too much. All but one coach left.

The 49ers owner Jed York signed off on all of this—essentially taking his still unproven-without-Harbaugh GM over the coach himself. In today’s NFL this was probably a monumental error.

Meanwhile in Philadelphia, a similar situation arose. Largely unproven former GM Howie Roseman—the man who had gone out and hired innovative coach Chip Kelly from college two years ago—continually fought Kelly for decision-making power behind the scenes. After a tremendous first season in 2013 when Kelly turned around the hapless Eagles and proved he could make his speed-oriented, collegiate system work in the pros, the team took a step back in 2014. Despite finishing 10-6, the Eagles missed the playoffs and limped down the stretch.

After the season, Roseman tried to make his power push by firing Vice President of Player Personnel Tom Gamble, a close Kelly-ally. Kelly defiantly walked right into owner Jeff Lurie’s office (who has long been president of the Roseman fan club) and demanded decision-making control. The assumption is that Kelly threatened to leave if he was denied. Two days later, after waffling in his own right, Lurie finally turned in the smart decision (perhaps with the San Francisco debacle in the back of his mind) and moved Roseman into a different role and placed Kelly in charge of personnel.

Football, after all, is a business. The success of the business has a lot to do with winning. Today, teams need an innovative coach and a consistent system with the proper players to use in it. The idea of the GM “giving” his coach players to “figure out ways to use” are ending. You won’t find that trend in many places five years from now.

The stories in San Francisco and Philadelphia have yet to be written—but assuming they play out as recent history suggests, NFL owners will have a regrettable and game-changing precedent to evaluate.