JERSEY CITY, N.J. - Kam Chancellor did an innocuous radio interview two years ago, never knowing what it would spawn. Asked to describe the style of play of the Seattle Seahawks secondary, the safety said the defenders "lay the boom" on opponents.
Fans suggested nicknames off the expression, and Chancellor scanned the replies on Twitter. One fan came up with "Legion of Boom" - similar to the Flyers' famed "Legion of Doom" line from the 1990s. Chancellor thought the nickname was catchy.
"Legion sounds pretty important, and boom was how we play, so it was the name we ran with," Chancellor said this past week.
"Before the name, we were always connected as a brotherhood. It was already there. The trust, the preparation we all had, the drive, the passion, and the Legion of Boom was just the icing on the cake."
The nickname describes the NFL's finest secondary, one that will try to foil Denver Broncos quarterback Peyton Manning and his record-setting offense in the Super Bowl on Sunday in East Rutherford, N.J.
In the Seahawks' locker room, there are welcome mats in front of the locker of every defensive back with "Legion of Boom" and each player's number. That was the idea of cornerback Richard Sherman, the most outspoken in the group - and perhaps the finest cornerback in the NFL. The No. 29 represents Earl Thomas, the former first-round pick who has developed into the NFL's best safety.
The rest of the group includes players who were overlooked or undervalued, yet now are part of the NFL's No. 1 pass defense and spark the league's top overall defense.
Thomas was the only player in the group selected before the fourth round of the draft, but the Seahawks defensive backfield has become the envy of the NFL. Broncos coach John Fox, a former defensive back, called it the "most talented" in the league. That lends the nickname credence. If the No. 18 pass defense in the NFL came up with a moniker for its secondary, it would be laughable. When the Seahawks do it, the nickname becomes so popular that even the abbreviated "LOB" suffices.
"The Legion of Boom is a legacy," Sherman said. "It's a legacy, it's a group, it's a legion, it's a vast army of individuals, and we have countless bodies behind us that are more than capable of doing the job."
Sherman is the playmaker of the group, and often the mouthpiece. The cornerback who proclaimed himself the best in the NFL after making a game-winning pass deflection in the NFC championship game led the NFL with eight interceptions despite being targeted fewer times than all but two of the 16 cornerbacks who finished with four or more interceptions.
For all of Sherman's accolades, Thomas might be the best player on the defense. The two were in competition for defensive player of the year. Sherman called Thomas "the fastest guy on the field, the most knowledgeable." He baits quarterbacks, plays deep in the defensive backfield, and can run sideline to sideline. Thomas called himself a new generation of safety and said no one else can be considered in his class because of his diversity of skills.
"I really take pride as far as coming up in run support, eliminate the explosive plays, and really giving my team every opportunity as far as points allowed," Thomas said.
Sherman called Chancellor "the enforcer, the punisher, the guy who sets the tone for the defense." That's a worthwhile description for the most imposing safety in the NFL. He's listed at 6-foot-3 and 232 pounds and can play in the box like a linebacker yet still thrive covering receivers in the open field.
The other starter in the group had been Brandon Browner, a 6-foot-4 cornerback who would have been a critical piece this week if he had not been suspended in December for violating the NFL's substance-abuse policy. Browner was replaced by Byron Maxwell, who has four interceptions and played like a top-level cornerback despite his previous backup status. The slot cornerback is Walter Thurmond, a former Oregon cornerback under Eagles coach Chip Kelly.
All seven defensive backs on the roster were acquired since Seahawks coach Pete Carroll arrived in Seattle in 2010. They almost all fit the tall-and-long prototype Carroll seeks, and they play an aggressive style that has drawn the ire of opponents who moan about its legality.
Sherman said the criticism is actually bitterness, and Carroll does not think it has merit, either. He said he's coaching defensive backs the same way he has since he was a North Carolina State assistant in 1980. He teaches them to bump receivers and try to disrupt routes, which is a common practice. But when the players doing it are as physical as the ones in Seattle, it's more noticeable.
"The play of our secondary has really been a process of developing each individual guy and bringing them together with the strengths that they bring," Carroll said. "I think it's been heralded because we've assembled a great group of guys that have rallied together, grown up together, and made each other better."
The Legion of Boom draws the attention, but the Seahawks' defensive prowess extends beyond the secondary. Carroll and general manager John Schneider sought to upgrade the pass rush during the offseason.
The youth on the Seahawks - especially in the secondary - means there is an abundance of players on affordable rookie contracts. The team had money to spend, and Schneider adeptly read the market. When the prices for top pass-rushing free agents Cliff Avril and Michael Bennett dropped, the Seahawks were able to add both.
They are atop Seattle's sack list this season. The interior linemen also pressure quarterbacks, with 323-pound defensive end Red Bryant able to play outside or inside. Seattle's 44 sacks tied for eighth in the NFL, and the pass rush will be critical on Sunday in trying to flummox Manning.
The linebackers are less-heralded. Middle linebacker Bobby Wagner has started since arriving in Seattle as a second-round pick in 2012 and had 120 tackles and five sacks this year. Bruce Irvin moved to strong-side linebacker after a productive rookie season and adds more athleticism to the field. Of the 24 defensive players on Seattle's roster, only two predate Carroll's and Schneider's arrival in Seattle. They built a defense that evolved as pieces continued to arrive.
"Once we got all these pieces in place," defensive end Chris Clemons said, "it was just a matter of going out and being able to play together."
Defensive coordinator Dan Quinn replaced Gus Bradley after Bradley was hired by the Jacksonville Jaguars following a courtship by the Eagles. Quinn spent the last two seasons running Florida's defense, but he had previously been a Seahawks assistant and continued to build the Seahawks' "4-3 under" system.
Quinn said the most marked development during his two years away from Seattle was the improvement of the safeties. That's where the defense starts. The Legion of Boom is the catalyst for the group.
The nickname has already become popular, and the players are already established in the NFL. But if the Legion of Boom can doom Manning on Sunday, its dominance will be validated.
"The Legion of Boom is going to have be on its 'A' game against Peyton," Sherman said. "If you're not on your 'A' game, we're going to have a long day."