I have noticed on one of my site, that no matter what I do about link building, nothing happens at all. My site is 4yrs old and RD250. That means, its quite a powerful site in my niche. Every backlink, and pbn is indexed. I didnt do anything like, gsa or forum links etc. My anchor text diversity is good, used a lot of brand and url anchors. My onsite is not overoptimized as i can see. I am blogging with unique content too. In 2016 November, my site started to fall like crazy from #1-2, to #6-7, and worse. For the last 3 months. I was trying to get myself up back in serp. I have made several press release. I earned about 20 natural links from high authority sites (sites in my country like Huffpost etc), created my own 20 domain pbn with a lot of content and decent metrics. Linked carefully with brand and url anchors. After 3 months nothing happening. Nothing noticeable positive movement. Any thoughts, whats causing this behaviour?