It's explained in the unofficial hacker news blog (http://jacquesmattheij.com/The+Unofficial+HN+FAQ#selfposts http://jacquesmattheij.com/The+Unofficial+HN+FAQ#s

It's explained in the unofficial hacker news blog (http://jacquesmattheij.com/The+Unofficial+HN+FAQ#selfposts http://jacquesmattheij.com/The+Unofficial+HN+FAQ#selfposts). Basically, it seems that submits that don't include an external link degrade faster than other submissions. EDIT: So this post too will probably go down the ranks pretty quickly because it fits in the same category.