By Danny O'Neil
The reason Earl Thomas is one of the team's most indispensable players on Seattle's roster is also the same reason you have to wonder about the team's depth at safety.
There is no one quite like Thomas. Not in this league, not on Seattle's roster.
In a league where many teams use safeties that are essentially interchangeable, Seattle is different. It has one safety who's as big as a linebacker in Kam Chancellor and another with the coverage skills that would allow him to play cornerback, but the speed and instincts that make him an elite safety.
Thomas has one-of-a-kind range, a center fielder who can line up 25 yards off the line of scrimmage, cover sideline to sideline and come crashing forward to the line of scrimmage when the situation calls for it.
He is unique, and not just because he is the only sub-6-foot starter in Seattle's secondary, but because of what his speed enables not just him to do, but Seattle's defense. Thomas is capable of being a single-high safety, meaning he's the one-man coverage policy at the back of the defense. It allows Seattle to put an extra defender in the box to defend the run if it wants or someone else underneath in coverage.
Not every safety can do that. In fact, not many can do that, and while Chris Maragos is also an absolute rocket of a runner, there's no true insurance behind Thomas. Then again, no team would. With Ed Reed and Troy Polamalu nearing the twilight of their respective careers, Kansas City's Eric Berry is the only other safety in the league whose tools compare to Thomas.
Chancellor is just as much a part of the foundation of Seattle's defense. The four-year extension Seattle signed him to this offseason speaks to that because while some teams have viewed safeties as the pawns of a defense, Seattle sees its pair as part of the bedrock.
The Seahawks have entered the regular season with four or more safeties on the 53-man roster in 10 of the past 11 seasons. Seattle kept five safeties last year, though that might be tough to do again given the depth at cornerback.
Locks: Earl Thomas, Kam Chancellor.
Seattle just might have the best starting safety tandem in the league with what appears to be very functional depth, though it's hard to tell. Thomas has yet to miss a game in his three seasons in the NFL while Chancellor has missed only one.
Seemingly safe: Chris Maragos, Jeron Johnson.
They were Seattle's backups last year, Maragos with incredible speed and Johnson with a tough, hard-nosed edge that allows him to play strong safety even though he weighs 20 pounds less than Chancellor. Neither is guaranteed a spot, but both have proven to be valuable special-teams contributors.
Intriguing candidates: Winston Guy, Deshawn Shead, Ray Polk.
Guy made the team last season as a seventh-round pick, and Seattle tried to use him as a designated pass rusher in both the regular-season opener at Arizona and the divisional playoff game at Atlanta. The result: Guy didn't have a sack in either game. The team believes he can be a playmaker, but he's going to have to prove that in training camp.
Shead is an intriguing athlete, a former decathlete at Portland State whom the team looked at as a cornerback last year. He's back playing safety this training camp, and someone worth watching.
Polk is an undrafted rookie out of Colorado, who certainly looks like he could play his way into consideration in the secondary. The concern is whether he can stay healthy.