It does look weird to me and i am sure someone might have the same problem/advantage regarding all the latest and initial Panda algo sweeps in SERPs.
The site in question was hit on the 24th of February first and got buried on the 12th of April when UK traffic died. All of the competitive search positions were blown off the first page and settled on 2nd and 3rd which killed all the traffic.
Ok, now, I am talking about the WMT average position reports. I tested all the filters and date ranges and noticed a significant drop in impressions and clicks but... Out of 4,987 search queries in the WMT report (Web-United States), most of them kept top 10 positions with some insignificant shifting on a daily basis (up and down 0.something) I have been monitoring these since February. The reports for the UK traffic are different, the Average positions were down but as of today, showing top 10 again.
I know there could be glitches in WMT but showing unreal reports with gains and looses for 4 months.... This site looks great according to WMT but we are still 80% down.
I am curious if this observation could be explained.
It does sound like a WMT reporting issue - but you may have noticed something telling about how the Panda devaluations are applied. After all, why would there be such a bug, eh?
We'll see if anyone else reports something similar. But in the meantime, I'm wondering about a related test you might be able to perform.
About 70% of search clicks these days are sending encoded position information in the referrer string. If you have access to your raw server logs, you can try clicking on one of your search results and seeing how that comes through in your server logs.
I do get occasional clicks from the 1st G page for the "pandalized" queries but they are so rare. I wouldn't even say that one single G server on .com has the positions indicated in WMT. Sometimes i get a spike on UK competitive phrase like "widget uk" for an hour or so. The remaining Google referrals come from multiple unpopular searches.
The strangest thing is that the impressions and clicks in WMT dropped about 80% but the positions remained.