It has taken me a while to figure why there was a recent and substantial loss of traffic to a lot of the pages on my site...(and yes, some of the traffic decline, I attribute to Google's recent SERP's redesign). But...
The number one, or two or three spot on Yahoo! that many of my site's pages used to be in have been demoted and replaced by pages (content deals) hosted by Yahoo! -- how convenient, AND this is along with Yahoo! making the replacements appear as regular search results, in their new-found number one positions.
It is truly a shame that no party seems to be watching over events like this, these days, with Yahoo!, or any other search engine for that matter.