This overrides a feature that I've seen described as the 'flame war detector'. If I understand the feature correctly, stories with a high ratio of comments to votes get a large ranking penalty. They tend to vanish suddenly and irreversibly from the front page when they pass the threshold, because they'll keep getting comments from participants, but don't have much opportunity to get any more votes from newcomers.
For instance, the "Google tips off cops..." story is ranked 12 here, but has fallen to around 200 in the normal ranking.
