[gervase]

A big factor of the ranking algorithm is related to the number of comments; as the number increases, the ranking of the article goes down. This is intended to penalize controversial articles that may result in flame wars.

This article has <200 comments, while the other one has >400; this is likely a significant factor in the falling ranking, in addition to the age.

I also believe that upvote velocity is weighted more heavily than upvote quantity, but I could be wrong there.

[kenjackson]

The comment algorithm seems backwards. I hope HN at least does sentiment analysis to see if the flavor of the comments tends toward being negative before downgrading the post.