Just a few examples of how the Penguin eclipsed MayDay (at least for us)...
May 2009 - total searched key phrases 10,000+
May 2010 - post mayday, total key phrases searched 9,000.
loss - 1,000 phrases, financial hit, substantial.
May 2011 - total searched key phrases 13,500+
May 2012 - post penguin, total key phrases searched 7,300
loss - 6,200 phrases, financial hit, devastating.
While we were not manually penalized in any way (according to Google's reply to our re-inclusion request)
the "quality" update has simply moved us down in almost half our keyphrases. Long tail is pretty much non-existent or makes no sense. As we've all observed, the thin ehow, about, voices, answers and MFA's have matriculated up while deep content has sunk. Seems like all that advice to build rich content for your users has backfired in our faces once again.
I'm tempted to keep chopping my content down to single sentences or shoot for a Flesch-Kincaid score of 120. That would be something like "See Bob Run". My current Flesch score is 68. That's very readable.
I have a feeling some of this drop is adsense / adwords motivated. There's no other logical explanation as to why Google would be happy with the current results. It's not a better user experience, unless your part of the Adwords team.
Oh, and the content aging that Mutt's has discussed seems to be out the window too. Much of what usurped our sites is scraped from much later than the original author date. [youtube.com
] (there's another MC video that better explains it, but I couldn't find it)