The Bengals doomed themselves from almost the very beginning in Week 10 when they lost to the Steelers in Cincinnati by a score of 24-17. Before Andy Dalton and the Bengals offense was able to get a single first down, the Steelers had already scored 14 points.
Of coures the Bengals almost came from behind to win the game but, in the end, the hole they dug themselves was too deep to get out of. They just ran out of time. If they want to win on Sunday to keep hopes alive to go to the playoffs as a wildcard, or even as the division winning team, the Bengals can't allow themselves to get down early.
The Bengals may be good enough to fall behind to the Browns and come back and win but they're not quite good enough yet to fall behind to the Steelers or Ravens and expect to win the game. To beat the Steelers on Sunday, the Bengals will need to come out of the gates with their foot on the gas pedal. If they can play like like they do in the second half, both on offense and defense, through the entire game, there aren't many teams that can hang with them and that includes the Steelers and Ravens.
If the Bengals win on Sunday, their chances of making it to the playoffs as a wildcard team go up a lot and let's not forget that they still have a chance at winning the division. To do that, though, they need to get through Pittsburgh with a win. The only way to beat the Steelers though it to play the entire game with minimal mistakes and stay close or ahead of Pittsburgh from the first whistle to the last.
I don't think there's a more important key to a Bengals victory than this one. If the Bengals want to win, they cannot fall behind early and force themselves to fight back late in the game.