Look at the successful teams in the NFL this year. The model for success for several of them is quite clear. The Giants, Titans, Jets (you can argue the degree of their success), Panthers, Ravens, and Steelers all have a pretty similar makeup, varying mostly in degrees of talent.
Each team has a solid or spectacular run game, indicating a good offensive line for the most part. The Steelers apparently run block reasonably, although they clearly don't pass protect well. Giants and Titans headline this category with both depth and talent. The Ravens have an oddball running game in that the most consistent contributor is built like Red Bryant, but they are getting the job done for the most part.
Stout, stout defense
All of these teams, with the exception of the Jets, are in the top 11 in YPG allowed. The Jets are 4th in run defense, however. Look at the D Lines of these teams though. Haynesworth, Jenkins, the entire Balty and NYG lines, and you find dominance at the line of scrimmage. 5 of these teams are in the top 8 in DVOA.
Competence at QB
No one here will put up Warner numbers, as their offenses are predicated on running the ball and executing when they need. Each of the guys here, although Flacco is still without a sample size, can lead a good drive.
So how does this stack up for Seattle?
Competent but aging and unspectacular running game. Adding an impact rookie to replace Morris' carries would be helpful. However, adding dominance along the O-Line is way more important.
Solid D- line, but in need more dominance. Giving Red and Mebane a year of development / health may be enough to start that process. We all recognize the need for a safety.
Hasselbeck is competent. He is also aging. Adding another wideout will help.
Draft early on big time O-lineman. Nab a safety on the first day and running back to boot. Then get the developmental QB for the future. Find a good route running wideout that isn't getting big time press due to a poor offense. You can always sign a guy like Antonio Bryant. Sign T. Suggs or draft some late round pash rush help. Win.