No one knows which of Wagner, Thomas, or Sherman is the best player on defense. I will point out, as I always do, that Seattle's pass defense was very bad for the first year and a half of Pete Carroll's tenure. It instantly became elite--by defensive passer rating--inflected at the game Sherman stepped onto the field his rookie season. Two thirds of NFL champions were top 3 in passer rating differential for their championship season, because pass defense wins championships. And Seattle is well aware of this, hence Sherman's contract. Winners look for marginal value by finding value discrepancies in the market. Seattle is brilliant at this and they still paid Sherman what they paid him.