wait for a moment, google has changed its index strategy, if your website has less original content, i am sorry to say you will lost the dominating position too.
Adding page rank will be added advantage. Also yahoo should give preference to the blogs in the search. Google update and display the results from blogs because it updates regularly. But yahoo display the result from old established website.
I just had a client ask me about his Yahoo and Bing Rankings. I told them exactly what you guys have mentioned here....