Why most of my sites never ranked well in Yahoo?

[bobo.cx]

I advise you do not bother with Yahoo, I have the same situation, two of my website ranking in Google is very good, on the three positions for several keywords, Yahoo, spend some time on the first page, and now they are losing like4 or 5.
This situation has been going on for months, I did not even use it.
Why? A site, one of my friends in the same niche and keyword rankings since last year (never change), the second page of a good location place of the master abandoned.
The conclusion? If you work hard, your page, search engine optimization and good fresh content, Yahoo will position you play and no one asked you.