Awarn - 8:12 pm on May 6, 2013 (gmt 0)
incrediBILL - I think it could be any of those or even Chrome. All they need is a track record of users clicking on a link and rapidly backing out and then they can determine that the link is not a good reflection on the site. That signals either bad site, bad link or something negative. So look at big sites that have had SEO work over the years. You get links then those links attract new links. Its the old Page Rank. But now maybe Google says fine let them link but if they aren't real relevant and if you have too much of those kind of links we penalize your site.
Fathom you say PENGUINized links are links dropped from the link graph... that's why you lose ranks. I think you not exactly correct. I am still on page one on Bing and Yahoo. Yet just like Ralph_Slate says there appears to be a -10 penalty. I can stay real constant about 10 to 12 spots below where I should be. That is not because of devalued links. That is because some automated function is implementing a -10 penalty. A one or 2 page BS site on a subject should out rank a site over 15K pages on the same subject matter. And when this hit I didn't make any major changes and any potential causes that I am aware of has already been tested.
Kind of all makes sense too. Google had issues with the Page Rank model that they were built on. Link building and directories manipulated the system. So why not implement a positive and negative aspect of Page Rank. There is definitely a penalty like Ralph_Slate describes.