Seattle signed Junior Siavii September 5, 2010. It was one of the lesser in a rash of last second moves. The most prominent, of course, was the sudden retirement of Alex Gibbs. For all intents and purposes, Seattle swapped Siavii for Kevin Vickerson. Vickerson had impressed in the preseason, was a much more natural substitute for both Colin Cole and Red Bryant, and went on to start 12 games for the Broncos, but something didn't click. Vickerson didn't "buy in" or whatever.
As long as we are willing to separate the signing of Siavii from the release of Vickerson, it was a solid move. Siavii is a bit of a misfit. He is built like a 3-4 end but primarily plays nose tackle. He was Jay Ratliff's proxy in the preseason, but he isn't nearly as explosive, quick or agile as Ratliff. Siavii saw most of his snaps in Seattle as an injury replacement for Colin Cole. He couldn't command two gaps like Cole, but wasn't an outright liability and is a better pass rusher.
On the surface, there isn't much reason to sign Siavii. Assuming a salary cap, signing middle-tier talents to free agent contracts, even reasonable ones, is a great way to nickel and dime yourself into poverty. If Seattle could instead draft a young player of a similar profile, it would benefit both from that player's comparatively cheap contract and upside. But players like Siavii are not common. That is one major reason Siavii was a second round pick in 2004. Players with his mass and length are always in demand and thus always in short supply. Seattle could find a better fit through the draft, but needn't force themselves to.
The Seahawks should probably float an offer and see if Siavii is interested. As I mentioned in the post about Palmer, for Seattle to become a great team again, it doesn't need sensational talent at every position. Siavii is not a sensational talent, but is neither blocking the development of or drafting of a sensational talent. He is a steady player, relatively young for a defensive lineman (or at least not old), with some chance of improving with a full camp and a better understanding of where he fits and what he's best at.