SEATTLE -- The mood inside the Seattle Seahawks locker room three weeks ago was predictably lighthearted for a reigning Super Bowl champion before a Thursday afternoon practice. Running back Marshawn Lynch raised the volume on the portable stereo in his cubicle, blaring rap throughout the cavernous space. Defensive end Michael Bennett shimmied on the opposite side of the room, slowly swaying to the pulsating beat. Cornerback Richard Sherman fidgeted with his cell phone a few feet away, stretching his slender frame along a plush lounge chair.

Everybody in the room seemed to be relaxing except for one person: free safety Earl Thomas. He sat quietly at his locker, headphones strapped to his ears, a black mouthpiece stuffed between his lips, fully dressed in practice jersey and sweatpants. Thomas stared straight ahead, displaying so much intensity that nobody dared enter his space.

Richard Sherman gets the publicity, but Earl Thomas might be the most crucial piece in Seattle's defense. Otto Greule Jr/Getty Images

"I'll probably talk to him in 10 minutes," Sherman said. "But not before that."

This kind of focus isn't random for the 25-year-old Thomas. This is what he does every day -- whether preparing for a playoff game or a simple walk-through session -- because that's how the NFL's best safety is wired.

"It's not about me being the best safety," Thomas said. "It's about me being the best defensive back ever. That's what I'm after. That's how you leave a mark on this game. When I think about the Hall of Fame and things like that, that's why I grind so hard. I know I have a chance to redefine this position."

Thomas' dedication is legendary to anybody who's known him throughout his career. This is a man with such purpose that he used to spend his Sunday mornings playing the organ in church after starring for the Texas Longhorns on Saturdays. That same focus helped make him a leader of a Seattle secondary affectionately known as "The Legion of Boom." It also should be especially valuable to a team that is hoping for a big second half to the season.

After fielding the league's best defense last season, Seattle has forced just 12 turnovers this year (it had a league-high 39 in 2013). The Seahawks have also surrendered 227 passing yards per game, compared to 172 last season.

"We don't feel like we've been as disruptive as we were," Seahawks coach Pete Carroll said. "Hopefully we'll get back to causing more problems."