Google brought joy and tears to webmasters across the globe last weekend with their Halloween 2010 update.

For me, this update rolled back about half the changes made in the June 2010 Update. This was very good for me, in that it undid a lot of damage that my sites took in that last update.

Not everyone is as happy as me with this update. I have spoken privately with several other webmasters who lost significant income due to this weekends change.

This change mostly hit this weekend, but some sites were affected as early as 20 October. PeterD wrote a scathing review of the results of this change in Who Benefits From Following Google's Guidelines? Google dropped one of his very old very whitehat sites. Being punished when you are innocent is a terrible feeling. In addition. One of my sites was punished the same day, but it is a newer site and it only dropped from 400 UV's/day to 200 UVs/day.

On the 29th, all hell broke loose. One of my medium sites was kicked out of the SERPs completely and another was damaged severely -- but at the same time one of my medium sites which had not been ranking was suddenly granted very reasonable rankings. At the same time, about 31 of my EMD (Exact Match Domains) were kicked out of the SERPS, but approximately 270 were added into the SERPs.

John Mu of Google claims that these changes are all part of the MayDay update. I did not believe this before, but John should be a fairly credible witness.

These are fairly massive changes and being able to watch changes of this magnitude is one advantage to having a portfolio of hundreds of thousands of pages across seventeen hundred sites. Unfortunately, although I am swamped with data, I have not been able to generate much actionable information from this data. and provide a useful example to show just how little sense appears to result from these updates. Last week, the .net was ranking and the .org was not; this week the opposite is true. Both sites feature similar designs, content, and links. I have several dozen examples just like these and none have thus far yielded an answer to the question "What does Google want?"

  • PeterD and I both lost old sites. I lost a couple of new sites also. But, dozens of my new sites were untouched by this update. Other people to whom I have spoken lost both old and new sites.
  • I and others lost and gained both small and large sites.
  • I and others lost sites which had recently added content without adding corresponding links to each new page. I lost a string of sites which I had recently grown from one page to eleven pages -- but a site where I recently grown from approximately 500 pages to over 1,000 pages without any additional link building was untouched.
  • A few of my sites with no content at all are now ranking very nicely.
  • Several of my EMD's with .biz and .us extensions are now ranking nicely.
  • One of my domains with an extra word prepended to it's target keyword is now ranking nicely for that keyword.

There may be a pattern where sites that add a lot of pages, without adding new links to each page, do not fit into Google's target profile. Sites with lots of pages with few links and a few pages with lots of links may be at risk. I am going to spread my promotion efforts more broadly across the deep pages of my sites for the next few months.

The only word with which I can honestly describe these updates is "randomness." There appears to be no method to Google's madness. There is no discernible pattern amongst either the sites which do well or the sites which do poorly. To an SEO, this is frustrating. I can only imagine the pain this much cause to individuals with only one web site. To have Google randomly derank your only website could drive a person mad.

As humans, we are evolutionarily adapted to spot patterns in data. This gives us such a survival advantage that the gene is actually over-emphasized and as a result we often see patterns even when they do not actually exist. That may be the greatest risk of these seemingly senseless updates and Google's almost neurotic secrecy.

So, if your sites lost rankings, you have my most sincere sympathies, but I unfortunately have very little in the way of actionable information to share with you.

Thoughts? Theories? Additional data from your own experience during these updates?