First we discover that Chris Carpenter is going for an MRI, which could be a huge blow to the Cardinals playoff chances. Now in Houston, Brad Lidge is officially out of the closer's job for a while.
Granted, Lidge wasn't that hot last year, and the Astros still came close to catching the Cardinals. Also granted, the Astros have other fine relievers, including Dan Wheeler, who will take over for the time being. This isn't going to destroy the team the same way that, say, Aaron Harang turning into Kyle Lohse would destroy the Reds.
But: the Astros have very little margin for error. They probably weren't in the race to begin with; for them to catch up to the Cubs, Brewers, and Cardinals, a lot of things would have to go right, and having Lidge return to dominant form would've been a nice start. As it is, I'm afraid El Caballo is headed toward another losing season, just in a different city.