Another QB bites the dust ...

Playing quarterback in the NFL these days has all the staying power of a Twitter post.

Through just two weeks, six quarterbacks have been benched for poor performance, and two have already been replaced. The Panthers will go with rookie Jimmy Clausen after two weak performances by Matt Moore, and the Bills have replaced Trent Edwards with Ryan FItzpatrick. 

Other quarterbacks to ride the pine so far: Vince Young of the Titans was benched in the second half for Kerry Collins; Jason Campbell was replaced by Bruce Gradkowski in Oakland; Arizona's Derek Anderson sat in the fourth quarter of a blowout loss in Atlanta; and David Garrard of Jacksonville was yanked in a blowout loss to the Chargers. 

And all that movement doesn't include the injury- and suspension-related absences of starters. Kevin Kolb missed yesterday's game against the Lions with a concussion, and was replaced by Michael Vick. And the Steelers suffered yet another injury - this one to Dennis Dixon - in yesterday's win over the Titans, leaving veteran Charlie Batch to play. The Steelers will be without Ben Roethlisberger for two more games as he serves out his suspension for violating the NFL's personal conduct policy.