Interesting side note at practice

So every day before practice begins the quarterbacks and centers work on their exchanges. The quarterbacks go through different drops with different play calls, but it's a way for them to become more acquainted with the center. Every day during training camp Cory Procter was among the centers in that drill. But he wasn't Tuesday. The four centers were Andre Gurode, Ryan Gibbons, Travis Bright and Duke Preston. I'm not sure what it means but Procter and Jon Kitna had the most exchange problems in the preseason and a botched snap cost the Cowboys Saturday's game against San Francisco.