I've about 10 EMD sites and none of them were hit in the EMD update. Now 3 days ago, I had one EMD site hit from #1 to #50 and dropped for all the terms.
It seems to me that Google has taken some sort of manual action on the website however there is no message in WMT.
So my questions are :
1. Since there is no message in WMT, can I be sure that Google has not taken Manual action. The symptoms are exactly as manual penalty, like bouncing between #50 and #70 results.
I've read somewhere where matt cutts said that 99% cases of manual action are notified via a message in WMT.
2. Have you seen a case when site was penalized but there was no message in WMT? Now when you sent in a reconsideration request, Google tells you about the penalty later?
3. One test I will request you to do on your EMD sites which were pushed down in the EMD update.
in search box and see if your site shows at page #1 or at Page #5 and further down. In my case my site is showing at page #5 and down further for different keywords so I'm isolating this case as a penalty.
As a conclusion, It seems to me like a manual action but there is no message in WMT. A similar discussion is also going on Traffic Planet and there is something going on.
In June of this year, Matt Cutts announced that 99% of people being impacted by a manual penalty imposed by a human Google reviewer were being notified. In the past Google did not do this and there is no guarantee how long they will do this.
To further confuse things there is a chance that a website can be impacted by a combination of an unannounced automated penalty & a notified manual penalty.
Since Google does not work for us and since many SEOs are seeking to exploit any weakness in Google's ranking algorithm I would not expect Google to make things easy for the SEO community.