One of my sites picked off without me even doing much as far as off page SEO is concerned. In the first months I concentrated on writing a ton of content targeting hundreds of different low competition keywords, and I managed to naturally rank a good portion of my articles, and didn't need to do much link building at all. The site constantly, though, attracts natural backlinks, and today, for the first time ever, I've noticed it to be a problem. A few days ago, my site was ranking #1 for a few thousand searches a month keyword with a few naturally gained backlinks. Today, though, it's on the 4th position. When I started to investigate what might have caused the drop in rankings, I noticed that the article had recently gained a new backlink from a pagerank 4 website. The problem is, though, that all of the backlinks to that article have keyword rich anchor texts. In fact, 80% of the anchors are an exact match for the keyword the article is targeting. What do you guys think? Has that article been hit by some kind of a penalty? Should I disavow that backlink? Should I build a few backlinks in order to diversify the anchor texts?