The Seahawks generally trade out of the bottom of the 1st round because there aren't any 1st rd players left.
In any given draft there are only about 15-20 1st rd graded players. So value wise it makes sense to trade down, and pick up an extra 4th. To still get a player of the same value, and get an extra pick out of it. It is a good strategy.
The Seahawks drafted Thomas & Okung without trading down in the 1st, if the talent is there they will pick. If it isn't they will trade down.
Its not about players at this point though. It is all about the coaching staff. Until that is fixed talking player acquisition is moot.