It likely won't come as a surprise, considering Mendenhall went down without being hit, and was unable to return to the game. It's unfortunate all the same, not just because the Steelers leading rusher will be out for the playoffs, but the fact an ACL tear is typically an eight-month recovery.
That may hinder his ability to prepare for the regular season in training camp. Incidentally, rookie RB Baron Batch tore his ACL in training camp this year, and is expected to be back in time for mini camp in May.
Mendenhall has one more year on his initial contract, and he is scheduled to be a free agent in 2013. This injury obviously will damage the value of that second contract, but he was running well in the opportunities he had this season. He was at 38 yards through one quarter in the game, putting him on pace to top 1,000 yards for the third consecutive season.
This is the second time in his career he's missed significant action. He broke his collar bone in Week 5 of his rookie season of 2008, and missed much of the team's run to the Super Bowl.
With this news in hand, the Steelers will likely keep Isaac Redman as their featured back, and work in Mewelde Moore (if healthy) and rookie John Clay. Moore has missed the last two games with a knee injury of his own, but fortunately for the Steelers, was not placed on Injured Reserve.
Redman was running well in the role Mendenhall would have had, but two fumbles on his final two carries got him put on the bench, and made what should have been a two-plus possession win a game in which Cleveland attempted a last-second pass that could have won it.
Redman hasn't shown much of a propensity to fumble in the past. Of his first 160 professional carries, he lost the ball only once. Turnovers are critical in the post-season, and Redman should expect the Broncos to aggressively attack the ball now.