The Steelers are carrying three quarterbacks -- starter Ben Roethlisberger, obviously, plus backups Byron Leftwich and Charlie Batch. They've also got Jerrod Johnson on the practice squad. That leaves them a bit thin on their 53-man roster, especially wide receiver. (The Steelers are only carrying four receivers -- Mike Wallace, Antonio Brown, Emmanuel Sanders and Jerricho Cotchery -- on their 53-man roster.) But head coach Mike Tomlin likes having three quarterbacks on the roster because it provides him with "comfort."
↵↵↵"I always find comfort in the three. When I walk up and down these hallways and look at pictures of the '70s Steelers, when there were 45-man rosters, I saw three quarterbacks in those pictures. So, that's a little bit of a history lesson for me."
↵
As the Post-Gazette points out, it's not very likely that two starting quarterbacks would get injured in the same game, but with three older quarterbacks, I suppose it's good to be careful.
↵For more on the Steelers, check out Behind The Steel Curtain.