^ lol, probably.
As far as the ranking goes, I think Ayu has just kind of... drifted away from what Japanese men want in a girlfriend. (Cute, young, occasionally helpless...)
I prefer to think that this is a sign that Ayu's kicking more ass, of course... that's just in my brain. It is in no way a good thing for her to be losing popularity.
On the other hand, although I don't listen to them, Mochida Kaori is very, very beautiful.