From another forum. Was said to have been pulled from a CBS article, but no link:
fits perfectly with the Seattle style of play, and the Seahawks deserve the right to have their talent evaluation trusted. They found guys who can fit into their strong rotations at defensive tackle and receiver in the third and fourth round, and in the fifth round grabbed a nose tackle who has first-round talent in Alabama's Jesse Williams.
Williams was off some teams' draft boards due to his knees -- including Dallas, which was looking hard at this position -- but others weren't nearly as concerned about his health. Even if his career isn't as long and robust as it might be without the medical red flag, in the fifth round, on a roster already worthy of a Super Bowl, it's a mitigated risk.