Seattle: no margin for error
The Seahawks had to play a perfect game. They had no room for error. They couldn't accomplish that. Pittsburgh's defense was too good for them.
The Steeler's had enough so that they didn't have to play a perfect game. Even if every call in the game that the Seahawks felt was unfair had gone against the Steelers, the Steelers still would have won.
Face it Hawk fans, you aren't good enough yet.