As Seattle’s vaunted defense fades into history, their collective legacy as one of the most important groups of players in NFL history is secure

They first stormed through the NFL six years ago, and no one had quite seen a defense like the Seattle Seahawks: free to run, free to hit and free to speak. They changed football on and off the field, bringing voice to a league of players who had been voiceless. And now that that Seattle’s defense is breaking apart, we should realize it is one of the most important groups of players in NFL history.

In a matter of hours on Wednesday the Seahawks effectively destroyed the defense that won one Super Bowl and nearly took another. The trade of defensive end Michael Bennett to Philadelphia and the reports that star cornerback Richard Sherman will soon be gone too signaled the official end of Seattle’s once-suffocating defense. But the moment had been coming for months. Great defenses don’t stay together long in the NFL, not in a league where the average career lasts barely more than three seasons. Players get hurt and a tight salary cap forces teams to make tough decisions.

Sherman tore his Achilles last season and Bennett was going to cost the team $6.6m against the cap next season. Safety Kam Chancellor, leader of the team’s secondary known as the Legion of Boom and defensive end Cliff Avril have career-threatening injuries. Safety Earl Thomas all but begged the Dallas Cowboys to come after him. After Seattle stumbled to a 9-7 record last year, missing the playoffs for the first time since 2011, the time to rebuild had come.

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But the legacy of the Seahawks defense will linger for decades. Not only did players like Sherman and Bennett and others challenge the way defense was played – with a ferocious pass rush and aggressive blanket pass coverage – they were unafraid to be themselves. They were loud, unafraid and wanted to be heard. And unlike most great teams in the past, where players stayed away from uncomfortable social issues, the Seahawks top players found they had a lot to say. They did not hold back.

It’s ironic their first Super Bowl trip came at the expense of a Colin Kaepernick interception because Seattle’s defensive players created an environment where it was OK to talk about things like race and injustice. They made it easier for Kaepernick to take his stand by kneeling for the national anthem and their support of the quarterback who had been a fierce rival allowed players on other teams to back Kaepernick themselves.

Much of this flowed from their coach Pete Carroll, who encouraged his players to speak about issues important to them. It was a huge change from the NFL’s old days where any mention of anything beyond the approved scripts of the head coach or team owner was considered a distraction. Carroll, who had failed runs as head coach of the Jets and Patriots before a highly successful decade as USC’s coach, returned to the NFL with a belief that if players could be themselves in the locker room they would be better on the field as well.

“If you want people to be their very best, train their minds,” Michael Gervais, a performance psychologist who advised Carroll and the Seahawks told me two years ago.

Facebook Twitter Pinterest Seahawks linebacker Bobby Wagner celebrates as team-mates Richard Sherman and Kam Chancellor look on. Photograph: Icon Sports Wire/Corbis via Getty Images

He bristled at the suggestion Carroll was allowing his players to speak out, saying that “allowing” was the wrong word. Rather, the coach was trying to get his players to understand who they were as people and “celebrate” that discovery.

“The hope is that we never reduce somebody to just a doer,” Gervais told me. “We want them to feel as if they are full humans and they have a meaningful purpose in their life. We want to amplify that in the most human way possible. It’s not easy because that is what the media does not want to hear or the public might not want to hear.”

Sherman, in particular, attacked perceptions of how a player should present himself, alternating between eloquent dialogues about essential matters and bombastic rants like the one he gave in his famous post-game interview following the last play that sent them to the Super Bowl in 2014. That moment and others in which he bellowed in the facemask of opponents made him a polarizing figure, blocking many from seeing a fierce intellect.

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Like many of his defensive team-mates, Sherman was an afterthought, a fifth-round draft pick who made himself the league’s best cornerback. This was the genius of general manager John Schneider who did not chase expensive free agents, choosing to find talented, overlooked players who would fit into Carroll’s philosophy of competing through every practice.

The Seattle defense was filled with players who had massive chips on their shoulders, who growled at past slights and burned to prove people wrong. They played on the boundaries of the rules, especially in the secondary where those in the Legion of Boom grabbed, pushed and hacked at receivers knowing the officials could never call a penalty every time. Their speed and height and desire made up for any flags that were thrown.

For a time, they were the most dangerous men on the field and the most enlightened off of it. They changed not only the game but a culture. In the end, they won one Super Bowl when they should have won two. And now they are done, scrapped for a rebuild.

But very much an important part of football history.