I've searched the forum for this problem and have seen similar issues. But I'm sure something is not right. Before with various search words many of the pages on my site would rank very high. Now with those same words my site is gone but everyone else’s page still have the same ranking, minus mine. Everything vanished on Jan. 1.
If I do a domain name search, it's picking up the page title and text from my link bar, which is an include page. But no description from meta or the content.
Of course it's not over, it's never over, G is always changing, but the point is many people who have legit and innocent sites have been dropped from google from some or all keywords. One of my own sites which was doing well for important keywords are nowhere to be seen... while others remain strong in the top ten. I don't think they're filters or penalizations at all, I think there are bugs in the algos G needs to fix.