Welcome to the Q&A Forum

Thank you both for your expertise!  Marie your article is a marvelous resource.  We will continue to dig into the GA but will also seriously consider pursuing the landing page suggestion with a nofollow link out.  Since we are rewriting content as well as redesigning, it seems that will produce the best chance to heal the site.

It could just be due to fluctuations in the size of the SEOmoz index and which of your links they indexed this month.