We had some bad luck too, though we did benefit from some BABIP.
Regardless, we've done well vs them practically all season and they have the worst pen in baseball. I think people are selling the Cards short. Their overall pitching is strong, even if they don't sport a 3 headed monster in the rotation. Considering a lot of our best work comes in the later innings, that proposes a problem.
The key against the Cards will be getting a lead against their starters. Their bullpen has the best FIP in baseball but the starters are a different story. They can be scored on and the Braves offense is quite a bit better.