There are so many plays in each game that it's hard to say a game was decided on a few plays but there were a couple of plays that looking back had a significant impact on the outcome of the game. So here are three plays that I think might have cost the Steelers a win last night.
Play 1: Let's go back to the 8:12 mark in the 2nd quarter, with the score 7-7 and the Steelers have a 1st and 10 at their own 44. Ben throws a pass to Ward and the initial call is an incomplete pass. Tomlin almost immediately throws out the challenge flag even though once the replay is shown it's pretty obvious that the call on the field was correct. The Steelers lose the challenge and their second timeout. Tomlin doesn't seem to have mastered the challenge system yet and this seems to be another example of that. Since the Steelers were on offense he basically has about 40 seconds to review the play upstairs with the coaching staff and make a decision to challenge the call. This play didn't doom the team on that drive but having an extra timeout would have come in very handing in final drive of the 2nd quarter.
Play 2: With the Steelers driving in the final minute of the first half and facing a 2nd and 10 from the Denver 31, Ben throws and pass to Ward who is pushed at the Denver 19. The play is brought back though because of a Kendall Simmons holding penalty and the Steelers are stuck back at the Denver 41. Ben would get sacked on the next play and with only one more timeout, would have to attempt a 65 yard field goal as time expired. The holding penalty easily cost the team at least 3 points if not a chance for a touchdown.
Play 3: With 43 seconds to go in the game and the Broncos facing a 3rd and 1 from their own 46, Cutler sneaks up the middle for an apparent first down, but James Harrison jumped offside and gave the Broncos an extra four yards and stopped the clock. The outcome might not have been different at all, but four yards would have turned a 49 yard field goal into a 54 yarder and without the clock stoppage the Broncos would have been more pressed for time.