Same story here. Of the links I "lost" there was not clear distinction of good or bad that went missing. It seemed pretty random in fact. Of course in my case I went from "few" to "very few"
Nice work... now maybe add something in your blog about yahoo and them banning/deindexing web sites.. with no explanation.. maybe they will fix that as well
Don't worry yahoo search engine don't give you a significant contribution to your traffic instead google.but you must try improve your site by good endeavor