Hi, I was having this question, since it is really strange. In this blog post it says is ELO-based.
I think that the post is old or wrong. Please note that this is not a complain or anything just an observation, but with the statistics at hand, score distribution does not follow an ELO-like distribution. The score gained in the first 5 spots is just big compared to all the other scores.
Maybe there is a point bonus for the first spots?how much? And a point bonus for each problem?
edit: Although ACRush’s case is notorious, because 5 winning streaks and now he has almost twice the score as the second person, what really brought my attention is the last page in the rankings