DETROIT -- Their defensive coordinator, Ray Rhodes, suffered a mild stroke before the start of the regular season and has had to relinquish a lot of his duties to linebackers coach John Marshall. Their starting free safety, Ken Hamlin, was lost after six games following a nightclub brawl that left him hospitalized with severe head injuries. And the Seahawks started the year with seven new defensive starters -- six of the front seven -- including an undersized rookie middle linebacker.
For most defenses, that's plenty to overcome in one season.
But it didn't stop there for Seattle. One of the team's major offseason acquisitions, linebacker Jamie Sharper, started half the season before going on injured reserve with a knee injury, forcing another rookie, LeRoy Hill, into the starting lineup. Injuries turned the left cornerback position into something of a revolving door, with Andre Dyson, Kelly Herndon and Jordan Babineaux all going in and out of the lineup.
Yet the NFC champion Seahawks still led the league in sacks (50), allowed the second-fewest points in franchise history for a non-strike year (271), and allowed one 100-yard rusher all year (Tiki Barber's 151 yards on Nov. 27).
Few outside of the Pacific Northwest could run off many of the Seahawks defenders' names; they just might be a modern-day "No-name defense." Meanwhile, the players just keep running to the football, letting their accomplishments in the face of adversity speak for themselves.
"The No. 1 thing is that they fly around," Steelers left tackle Marvel Smith said. "You look at them on film and they really make a lot of effort plays, like chasing a running back down from behind. Their defensive ends really get up the field. Their whole front seven is really fast. There may not be a lot of people who know a lot about them, and there's a lot of people sleeping on them, but we certainly know about how good they are."
Seattle's defense, led by rookie sensation Lofa Tatupu at middle linebacker ("If that guy stays healthy," Steelers right guard Kendall Simmons said, "he will be one of the best linebackers to ever play this game"), improved to a tie for 16th this season from 26th in 2004; finished fifth against the run while allowing just five rushing touchdowns; and surrendered (including the postseason) only 20 touchdown passes. The reason is simple: speed. And as a result of the defensive overhaul, the Seahawks' defense, while perhaps not the most talented unit Seattle has had, is devoid of the selfishness -- and thus the freelancing -- that held it back in years past.
"We've thrown the individual out this year," strong safety Michael Boulware said.
Defensive end Grant Wistrom said, "Guys are spending a lot more time in film study and guys are just playing the defense the way that it should be played, and that's 100 miles per hour."
For three hours or so Sunday, in Super Bowl XL, Seattle's defense has to overcome one final obstacle if the Seahawks are to deliver the franchise's first world championship. AFC champion Pittsburgh has averaged nearly 29 points during its seven-game win streak, with the offense shedding its conservative label as Ben Roethlisberger compiled a 124.8 passer rating, with seven touchdowns and one interception, in three postseason road wins.
Still, if the Seahawks are to win Sunday's game, the key, they feel, is to stop Pittsburgh's running game. Use their speed up front to penetrate the Steelers' offensive line and stop Jerome "The Bus" Bettis quickly before his wheels get going. Negate "Fast" Willie Parker's speed with that of the their linebacker corps. "The guys on the backside really have to keep the edge," Wistrom said. They must render Pittsburgh's dangerous play-action passing game ineffective by stuffing the run and putting Big Ben in third-and-long situations. "We can't let their running game get started," defensive tackle Rocky Bernard said.
Then, the Seahawks must get pressure on the passer with an undersized, but aggressive and quick defensive line rotation that can generate pressure on its own -- the group combined for 32½ of Seattle's 50 sacks -- or come with the occasional five- or six-man blitz. And they must stay with Pittsburgh's receivers if and when Roethlisberger escapes the pocket.
All easier said than done, yes. But if the Seahawks have proved anything this year, it's that there ain't no mountain high enough that their defense can't climb it.
"The Seahawks' defense is just as good as any other defense if not better," Boulware said. "We have a point to prove on Sunday. Hopefully we can get it done and get a little respect around the league."
Michael Smith is a senior writer for ESPN.com.