On 4th of September, one of my old subdomains got a -90% penalty out of the blue.
Last month, after a lot of work and no results, I was getting desperate, so... got nothing else to lose!
My site is scrapped like hell since 2001 and only in the last years I've started to block robots, so my content is on many, many, many Whois Protected
sites from direct scrapping and from RSS (aggregators). What I did, step by step:
x.example.net - OLD
y.example.net - NEW
I've moved (301 redirect) all the content created until 2010 from x.example.net
Results? See the pictures. New subdomain
...] Old subdomain
As you can see, the old domain had some thinking, but throwing away another part of the old content (410) helped.
It took Google about one month to discover that the content from the new subdomain is pretty old and problematic, now the new y.example.net is crashed.
So... If you already removed the thin content, you have a big disavow tool and you did a lot of nofollow on insite links, than this is the next step.
Now... I need another miracle for Panda, (-60% traffic slowly since March 2013), but kids, that is a story for another day! ;)
[edited by: brotherhood_of_LAN at 8:50 pm (utc) on May 6, 2014]
[edit reason] changes to example. [/edit]