Yeah, but instead of looking at if something got into the top-20 (binary 1/0), he's saying that they should have modelled the absolute score of an article. This would give you a way of weeding out the cruft that hits the front page and disappears quickly.
Another way of looking at it would be the amount of time that a post spends on the front page.
Another way of looking at it would be the amount of time that a post spends on the front page.