Arizal - 10:43 am on Oct 15, 2010 (gmt 0)
I have some site which experienced similar drops on June 2nd, most of them are back to normal now. Furthermore, I have some sites still some sites which were affected after June the 2nd in the very same way, after some kind of bold link building campaigns.
A lose collection of observations so far:
- Anchor text over optimization seems to be often a cause, it helped some times to add more links on trusted and other sites with other, yet relevant anchor text. (Decreasing the percentage of optimized anchor text, as a result the filter should not be triggered any more after some time). Usually such a site can recover in about 3 - 4 weeks.
- Changing servers/IP - I saw this helped for quite some time (ca. 1 - 2 days) and in my case I thought first it was triggered that I had to few class-c diversity which changed after change of ip. As I moved another site with some delay c-class popularity changed for maybe a day. I am however not absolutely sure about this, too.
- Site coming back for some 2 days and then dropping again: in most cases a sign that the site soon (1 - 2 weeks more waiting) will come back
- To fast link velocity could be a trigger, too, yet I am not sure about how to dis tangle the effects from anchor text optimization and building too many links too fast.
- I have the impression that nofollow links with over optimized anchor text can do the same harm.
So, in generall, adding new links with substantially different anchor texts or just the domainname helped in most cases, yet not in all.
The sites in question had actually all low backlink profiles and were pretty new (less than a year). Overall I must say that after some downs and dancing weeks after Mayday in June most of my sites have really benefited from the Algo updates (all are informational niche sites with really pretty good content, yet not the best backlink profiles).