OT but I really don't understand these types of questions. The possible answers range from "because the ranking works that way" to "someone with privileges wanted it that way". On either end of the spectrum, the real question remains: so what? What difference does it make why a particular post is in a particular position? If the title seems interesting, you click on it. If not, you move on.

I don't mean to question you in particular. It just seems like such a trivial concern to me that I truly can't understand why someone might possibly care.