All my other pages on the site still rank consistently high (usually on the first page for obvious search phrases) except for the two affected pages.
Also it has lots of well researched content with links from universities and such.
So I don't know if it's different from when all of a good solid site has the same problem as happened to a different site of mine during Bourbon.
Seems like if we could figure out why a page plunges like this it might help figure out why a whole site can go as well.
Losing a page is annoying but I know too well the same unexplained thing can happen to a whole site.