The fault in his logic lies right here:
Golden Tate, defensive linemen Red Bryant, Chris Clemons and Clinton McDonald, cornerbacks Brandon Browner and Walter Thurmond, safety Chris Maragos, tight end Kellen Davis and offensive linemen Paul McQuistan and Breno Giacomini all signed elsewhere. Maybe none of those guys individually will make the Seahawks lose sleep, but that list contains a lot of solid players and considering there wasn't one major free-agent addition, the roster has to be considered worse.
This completely ignores potential contributors added through the draft (ex: Richardson, Britt, Marsh), players returning from injury (ex: Scruggs, J. Hill, Simon....even Harvin), and highly-talented players groomed to step up into bigger roles (ex: C. Michael, Bailey/Bowie, Irvin, Lane, Shead, etc.). Never mind Kevin Williams, Eric Winston, Terrell Thomas....