My site is been languishing since Panda 1 (Feb 2011) in spite of an incredible amount of change (rewriting content, removing/redirecting thin content, nailing down technical issues, redesign, improving engagement).
In fact it took a further blow in the Panda update of June 8. Some folks have suggested it might suffering a dupe content penalty due to this:
A site: command on Google shows around 900 pages. When you page thru the results you get to about 540 and then get the message "...we have omitted some results very similar..." When you click "repeat the search", the actual listed results are the same (about 540).
So what's with the phantom 360 odd pages?