Seattle had zero creativity in the red zone
I like offensive coordinator Shane Waldron a bunch and he can be creative, especially in the way he uses tight ends. That's what made Seattle's red zone offense against the Bengals so weird. The Seahawks went 1-5 in the red zone (I guess you could say 2 for 5 but one of those trips would be a field goal that was made after Seattle had been moved back outside the 20-yard line) and there wasn't a lot for Cincinnati's defense to guess at what was going to happen.
Maybe part of the issue was the Seahawks' first drive. Seattle drove down the field, having just one negative play, and then scored a touchdown after having two 6-yard runs inside the 20. Maybe Waldron thought Seattle would just run the ball once close to the end zone. But then that changed too and the plan was for Geno Smith to drop back and try to throw passes for touchdowns.
The problem there was that most of those pass plays weren't quick-developing plays but instead had routes open with Smith trying to stand in the pocket for several seconds. But Smith wasn't innocent about what happened in the red zone either, of course. He was sacked a couple of times, but one was when he had several seconds to either throw to a receiver or throw the ball away, and then he ran into the rush. On another play, Smith threw an atrocious pass in the direction of Jaxon Smith-Njigba that was easily intercepted.
Still, had Seattle used some different alignments or tried something different other than the same plays that weren't working, maybe the Seahawks get one more touchdown. And one more touchdown would have won the game.