Thanks MadScientist. I'll certainly raise that with them
Given that this is a well established name in its sector, Google is only 40% of their traffic. But doing the site operator shows that Google only has 12,000+ of their pages, compared to Yahoo which has 70,000+. They don't have a working sitemap in GWT since the redesign a year ago -- their IT just didn't think it's a top priority (I know, horrors!)
Some patterns re their traffic drop:
1. Traffic for branded keywords remain strong.
2. Keywords where the landing page is their home page are not affected
3. Keywords for their key products (books) are not affected
4. Keywords most affected pertain to the old papers (2005 and older). These are the oldies but goodies that get the most traffic
5. Names of their experts (those with long bios + long list of papers published) have disappeared; other staff member pages including former experts are still ranking at the top
Traffic for some keywords started falling on Sunday, but most fell on Tuesday.