I've been corresponding with the founder of one of the salary cap sites and apparently there was another adjustment just prior to free agency from the $13.2M figure that's been widely reported. In fact, the Seahawks got another $1M or so adjusted upward so our total cap is $137.2M. I've been posting updates in the stickied thread up top but I thought this was important enough to post by itself.
Seahawks right now have about $6.5M in available space, even after rookies are signed they would have over $6M. Probably enough to sign another mid-level veteran and work out an extension with Chancellor if the parties are willing.