Ya know, I have had this issue recently as well, but not necessarily with Ezine. I was ranking first page on some terms and after adding links, my URL disappeared and was replaced with the pages that had links to my site. I kind of recovered a bit by deleting some off-site deep-links, adding new content, and getting more backlinks for the top of the domain.
Actually Google found the portion of content on ezine more relevant and reliable than your site as to post an article on ezine you have to pass several stages after which it is published. You indeed committed a mistake which can be reversed by deleting your article from ezine. But if someone has copied the same article and posted into other article directories or blogs still your site ranking and placement goes down.
Yes, I'm still ranking #1 for my site name. However, I have noticed that my rankings have gone down now across the board. All of my pages seem to be getting ranked lower. Also, in Google webmaster tools, I notice that the number of links to my site just disappears after a while. Do they only keep links for a month or so?