Earlier quoted context omitted.
It must have been heavily flagged. It's been lower than it should have been from the start. Admittedly the title of the submission isn't great so - if I'm being charitable - it's because users flagged based on title only.
It's been on the front page for hours now.
Last evening GMT this submission was in fourth place when by points/comments/age it should have been first.
User flagging is the most charitable interpretation.
edit: now at position 54, 1078 points, 315 comments, 16 hours ago. At position 53 is a story from 17 hours ago, 69 points, 13 comments (https://news.ycombinator.com/item?id=10466419)