If it were that easy, every competitor would be spending all of their time trashing and trying to take out their other competitors. I think you need to look a little closer to home if you've been actively optimizing said site. It is possible that changes you made several months ago were more recently picked up by the search engines.
Review your past work on the site and see if you can pinpoint something you accidentally changed. Posting the URL as joshz recommended will surely get you a better response.
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"Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime." Chinese Proverb