At the moment, this post has 4 upvotes and yet it is in the #7 place on the front page of Hacker News. How is that possible? 4 upvotes gets a post that high on the front page?
Some of the details are part of the secret sauce, but kens did a blackbox analysis to try to guess more details. It's an old post, so many details may have changed since it was published, but I guess the main ideas remain.
http://www.righto.com/2009/06/how-does-newsyc-ranking-work.h...
http://www.righto.com/2013/11/how-hacker-news-ranking-really...
And over time just built up some points. Probably just shot up because of 4 upvotes at the same time.
As others submit the same stories, the first poster has their story upvoted.
Result is that this user is credited nearly all of the upvotes from a few core sites that have content of interest to the HN audience.