Planet13 - 4:38 pm on May 13, 2012 (gmt 0)
I'd say Penguin acted like a surgeon in my case.
How do you rank for the plural versions of those words (if they have a plural version)?
For one page, I stopped ranking for the plural version, but it still ranks for the singular version.
Go figure. They are just different by one letter (an s at the end).
For the plural version, our home page now ranks instead AT THE SAME PLACE as the internal page used to rank.
Do you have lots of INTERNAL links with the same anchor text pointing to those pages?