The Bengals did fight through the injuries, even leading the steelers in the first half. The fact was that the Bengals could only hold down such an evenly-matched opponent for so long without their best player. There are very few teams who can keep it together when such an event occurs. I mean, you saw what happened without Ben at the helm for the steelers, it's the same sort of situation.
Effort doesn't always equal a win when you're outmatched.