Google Indexed URLs for Terms Have Changed Causing Huge SERP Drop

[EvergladesDirect]

We haven't made any significant changes to our website, however the pages that google has indexed for our critical keywords have changed to pages that have caused our SERP to drop dramatically for those pages.

In some cases, the changes make no sense at all.  For example, one of our terms that used to be indexed to our homepage is now indexed to a dead category page that has nothing on it.

One of our biggest terms, where we were 9th, changed and is now indexed to our FAQ.  As a result, we now rank 44th.

This is having a MAJOR impact on our business so any help on why this sudden change happened and what we can do to combat it is greatly appreciated.

[RyanKent]

Your answer will likely be found here: http://www.seomoz.org/blog/wrong-page-ranking-in-the-results-6-common-causes-5-solutions

[EvergladesDirect]

Thanks for the link, we are on that already.  I was just wondering why all of a sudden the pages that have been indexed for years changed.

[RyanKent]

Google makes about 500 changes to their algorithms each year. It is likely that either one of those changes, or a change made with your site or backlinks, caused the change in results.

If you can share the URLs and keywords involved then more direct feedback can be offered.