Why this show is not in the top rated?

Like you probably know, IMDb uses many filters when they determine the "weighted rating", and even more filters when they compile their lists. They keep them to themselves to prevent manipulation, so I (of course) don't know why. I have some theories though.
- Regular voters. We don't know how they define who these are, but this show probably has a significantly lower rating among these.
- Nationality. I don't know if this is factor, but I'm pretty sure that it matters if a show/movie scores vastly higher in its home country than in the rest of the world. The turkish shows (Leyla ile mecnun, Isler Gucler, and Behzat) seems to imply that this is important.
- They probably have many other filters too - there could be many reasons.