Originally Posted by HHI Golf Guy

Any rankings changes you see are not part of a new algo or filter. They are a result of Google changing the value of incoming links. Google is still targeting paid links that d not use rel=nofollow or some other means to make sure the link cannot be crawled.

You also need to remember that even if you do not by links, one of your link partners or their link partners may have lost link pop because of link buying or selling. Your site may be feeling the trickle down effect.