maddawg - 3:12 pm on Apr 25, 2012 (gmt 0)
These tweaks are hitting tactics that webmasters have been using for years to rank high in Google. Most of the sites being hit were using anchor text links from low quality sites to rank for their keywords. These tactics were not borderline, as their intent was 100% for ranking, but Google had trouble detecting it until now.
Well-branded sites who did not engage in these tactics are benefiting quite a bit.