@aristotle, if you'd like to contact me offline, I can try and prove to you that yes, I am telling everything I know about my story. Obviously I don't know what Google knows (or thinks it knows), so that is why I am trying to develop theories as to why I was hit with a 50% to 80% drop in Google referrals on 4/24.
I'd lovefor someone to figure out why that happened. When I posted on the Google forums - which, as you know, are the height of cynicism and arrogance - no one could find any specific Penguin-related problems with my site, so they settled on "even though it happened on 4/24, it was just a coincidence, and you were really hit with Panda because your site isn't very good" - and then the discussion veered off into diatribes of why my site in general isn't very good - which, of course, was a rabbit hole, because I have the online reputation to prove that people do in fact value and trust my site (far beyond Wikipedia).
No one ever turned up anything that matched any of the Penguin triggers. In fact, John Mueller himself said "I don't see anything wrong with your site" and gave the generic advice to "make it the best it can be" - which is like a doctor telling you to eat right and exercise when you come to him with complaints of pains in your chest. Reading between the lines, to me this meant that Mueller didn't know, but couldn't exactly say that because that would signal that he didn't understand the impacts of their algorithms.
I don't believe in the "it was coincidentally Panda on the Penguin day" theory, so my investigation continues to focus on Penguin and what makes my site different from most others. The Wikipedia/DMOZ links are something that stand out to me. It seems problematic that of my 100,000 most recent links, 75% are from Wikipedia spammers. Does anyone else here have such a situation?