The rules are simple: a user submits a link and title, the community upvote and downvote this submission.
Yes the rules are simple (they're actually not but they can be simplified), but yet the article seems to have gotten them wrong, submissions don't have downvotes.
I starting skimming after that, it appears the metric he's using is number of upvotes, this is NOT the relevant metric, posters are looking for exposure - what they want is a position on the front page. While those things are linked they're not the same. Would also probably want to take into account pageviews on weekends vs. weekdays as this affects exposure. Maybe it correlates to votes/no. of submissions, but maybe more people passively consume on weekends or weekdays.