Teachme2play: I think that the score calculation should be slightly different. It's Glicko, isn't it?

No, it's not. It's neither Glicko (which would take into account how recent your rating is - if you've played a lot recently, your rating will change much less (aka, is more stable) than if you haven't played a lot recently), nor is it even Elo based (which does account for how big the score was in a match - with Elo, you can actually gain rating points while losing the match: for instance, if the rating difference say you ought to lose the match 7-3, but you only lose 6-4, you win rating points; the winner of the match looses points).

What system BK uses, I do not know. But based on observations how rating points are calculated, I can say it's neither Elo, nor Glicko (note that Glicko also takes into account which how many points a match has been won).