Ask PG, HN: Is someone tampering with article positions?

Can someone explain to me how the same algorithm can classify a highly controversial topic like the Monsanto story[1] in place 128 while another story[2] of the same publication time with less points and much less comments be on place 29 on the frontpage at the same time?

[1]: http://imgur.com/2IU0JCD

[2]: http://imgur.com/XspkTjs