Aaron Wall put up a post about a new Google filter that causes people with high ranking terms to be bumped down to position #6. There is also a thread at Webmaster World about this phenomenon. This is still reasonably speculative in nature, but there are a lot of people who have seen this.
Aaron offers some really interesting speculation about why this may be occurring. The most interesting theory was the notion that it was an anchor text problem. Here is what Aaron had to say:
I think this issue is likely tied to a stagnant link profile with a too tightly aligned anchor text profile, with the anchor text being overly-optimized when compared against competing sites.
Whether or not this is occurring now, this makes complete sense. It is well within Google’s (or any other search engine’s) ability to detect an unusually high density of one form of anchor text to a given domain. For example, if your site is called yourdomain.com, and you sell widgets, and the anchor text in 48 or your 65 links says “Widgets on Sale”, this is not natural.
Most of the links to your site should be the name of your domain itself (i.e. in this example, “yourdomain”). Such a distribution of anchor text is a flag that the anchor text of your links are being artificially influenced. How is that done? Why by purchasing links, or by heavy duty link swapping.
This is potentially another step in Google’s stepped up war against the practice of link buying. I have long maintained that the main advantage the link buying has over natural links is the fact that people who buy links get to specify the exact (keyword rich) anchor text. used. Looking for unnatural patterns of anchor text provides a backdoor into detecting people who are purchasing links.
It might be a bit heavy handed for Google to ban a site based on this type of evidence, but reducing the impact of anchor text on rankings when there is an unnatural distribution in play still helps them meet their goal. After all, even if the unnatural acnhor text campaign does not represent the result of a link buying campaign, and all those keyword laden links are in fact completely natural, it might still provide better relevance for Google to filter in this manner.
Thinking about this further, this might be a simple search quality adjustment for skewed anchor text distribution. If it affects paid links, from Google’s perspective, this might just be a bonus.