@ Ralph_Slate - I finally realized you said you "recovered"... which supports the conclusion made months earlier.
Thanks for posting all of these details. Looking at your site, I don't see any specific technical issues, or general issues with the links to your site. I can, however, imagine that our algorithms might have some trouble understanding the unique value of your website in comparison to other, similar sites (especially considering that the content is primarily aggregated statistics). My general recommendation would be to continue working on your website, making it the best site of its kind. There's no single change that you'd need to make, so I'd really look at your site overall and see where you could make improvements on a general level -- you mentioned that you might have some thin pages, perhaps that's a place to start (or at least, to try things out with A/B tests, etc).
It's important to note PENGUIN 4 will be coming out and if you haven't made substantial improvements to your domain (in generally) you can easily be back to the problems of last year.