The Seahawks had a poor 3rd down performance to close the Bengals game, finishing 1 of 7 on their final 3rd down chances after going 4 of 6 to start the game.
The Seahawks had two scoring drives where they avoided 3rd down altogether (their field goal drive before halftime and the Rawls touchdown play, which was the first play of the drive). According to my records, the biggest hole in the Seahawks 3rd down game is in the 3-6 yards to go distance -- with a miserable 29% success-rate in this down and distance.
Seattle did show improvement in the Bengals game, posting their best performance from this down and distance, and going 50% (3 of 6) from this range.