Did some investigation concerning the keywords I am tracking, but it seems that we are the only ones who are actually interested in trying to determine the cause...
Like Google, Yahoo is also very tricky. I think that older websites are maybe the most valuable and appreciated. A yahoo or google dance can push you with some places but than you will be down again. And the questions is why were you up? Because now when you are down it is a normal situation. I hope that you will get up again but sometimes time is more valuable than links and content.