My site went from #3 to #2 to #1 to #10 in Google.nl

[VisualSense]

I have a site which has been #3 in Google.nl for a certain long tail phrase for pretty long. After I optimized my site some more for this specific phrase I went to #2 and eventually some weeks later to #1.

But when I finally became #1, the celebration was short, as two weeks thereafter I dropped to #10 where I have been stuck for several weeks now...

Can this be some sort of over optimization penalty? I personally don't think so as I hardly created links with the anchor, or a variation of it. On page also seems pretty much in order to me.

Also, the site is on a exact match domain and used to rank for it, but doesn't even rank in the top #100 anymore.

Any advice?

PS: I rather don't publish the URL, but if anyone can help out I have no problem sending it in a private message, including the phrase in question.

[MarieHaynes]

I've seen the opposite happen a lot where I am say #5 and then I drop down to #25 and then all of a sudden I am #1.  I have a theory that when Google is about to make a change it does some sort of testing to see what happens when it is dropped out of the picture.  So, it's like they are saying, "Let's see what other sites get clicked on when this one is out of the picture." If there's no clear favorite then yours goes back up higher.  It's possible that you were on the other side of this and your competitor's site is the one that was promoted.

However, it's also possible that your site was a Panda casualty.  When did the rankings start to suffer?

[VisualSense]

Panda is out of the question as this site concerns a Dutch site and the SE is Google.nl.

[MarieHaynes]

Are you absolutely sure?  There was a wave of Panda that hit non-US sites on the week of April 11th (or thereabouts).  Does that coincide with your drop?