Some of my sites had suffered from it, but others (very old ones) got on the top positions. Domain age might be the cause of such changes. As for the article - it's not worth a s* for webmaster. A really nice piece of webmasters knowledge, don't ya think?
Rankings are greatly affected due to Google changing Algorithms..... If you want your page be back.. Build more quality links 'coz links is primary factor with regards to Google's Ranking....