Can anyone explain why this apparently excellent article, 3 hours old, with 305 points and 304 comments, is currently on page 16 (!) of HN - while the article i

Can anyone explain why this apparently excellent article, 3 hours old, with 305 points and 304 comments, is currently on page 16 (!) of HN - while the article it's a reply to, 8 hours old, 127 points, 240 comments, is still on the front page? I thought articles were marked down with the passage of time and by the flamewar coefficient (comments-to-points ratio) but neither goes anywhere near explaining this. Is there something massively wrong with it that I'm not seeing? I thought it seemed like good analysis and a great explainer for the subject.