Great (and long) thread!
On April 14th I lost about 60% of traffic on a Danish site - all of the loss was Google long tail. The Google traffic had been stable or slowly increasing for the last 2½ years.
So I guess the good questions then are:
- Did I do something wrong so Google devaluated the site
- Is is temporary because of a Google update
- Is it because of a change in Google algorithm
Almost all inbound links are natural, so I rule out spammy links to be the cause.
The site has a high percentage of thin content pages, about 90% of the pages is company profiles with little more than a company name, address, phone and website address - all within a particular vertical. The titles are optimized for searches on company names, location and the vertical name - which worked fine for the past years and brought the long tail traffic.
The rest of the site has quality content on the pages - articles, unique company descriptions ect. But because of the high percentage of thin pages I'm not completely suprised if Google devaluated it. I would still like to know for which of the above reasons.
Another interesting thing is that I still get some long tail traffic, just less of it. Nearly all my refferers from Google are now from Google Maps. If I do a search for a company I used to rank for my site is burried down on page 3 or much further down. But if I click the result from local search a link to that companys page on my site is at top nearly every time.
I'm not sure my case is similar to others reported here - for example I have seen no changes in traffic up and down.
The sudden loss of specifically Google long tail on April 14th after a long stable run in Google is what I found similar to others.