Content_ed - 7:20 pm on Feb 28, 2011 (gmt 0)
I'd like to believe it's not a penalty, but I don't see why you think a penalty would produce a set drop like minus three positions or minus ten. A penalty that simply knocks down whatever ultimate score Google assigns for the sake of ranking a particular phrase would look random for different phrases and pages depending on the competition.
I tend to suspect it's a penalty because my sites that were hit, a 10 year and a 15 year old site with all original content, low numbers of pages, and pure organic linking, are not very similar to the other legit sites I've seen that were hit.
One site has no advertsing beyond some Amazon links to buy published books. The subjects are mixed. The page lengths are much longer than most sites, usually a couple thousand words, but there are some shorter pages as well. Some are illustrated, some not, some include YouTube videos, most don't, some are blog posts, most ar not. Yet the overall result is remarkably uniform, all pages are seeing greatly reduced traffic.
If Google were evaluating the scoring for pages differently, I'd expect some pages to go up and other to go down. For them all to go down, it looks like a penalty.