Whitey - 11:19 pm on May 30, 2010 (gmt 0)

when you click through the relevance was really weak or absent

Can you elaborate on this some more?

Relevance is something that I see as critical , but perhaps we need to be a bit tighter in what we define as this.

Navigational structures ?
Keyword density ?
External linking ?
Internal linking ?

Some of the demonstrated sites mentioned as being hit , may have difficult in their heirarchy of semantics , meaning that if the site and/or the page is supposed to be about " a " , by the time it drills down to weaker pages to " z " the relevance signals have also become very weak.

My speculative hunch is that this is where the change is.