This picture has been floating around the interwebs, along with claims that the idea was to create a sense of increasing decay in the show's logo:
However, the logo seems to have become more intact in season 2 than it was in season 1, and at any rate, the supposed "decay" is uneven and inconsistent - portions of the text that were damaged in one season are apparently repaired in subsequent seasons (e.g., the final "D" in seasons 5-6).