Now forget May.
Each of my blogs lost half of normal visitors!
Each of my blogs got back to normal.
So what happened June 2nd?
Here is the answer. There was a Panda 4.0 update that hit on May 20.
More Panda 4.0 Findings: Syndication, User Engagement, Indexation & Keyword Hoarding - SEW
I checked my traffic for May and found that some sites lost thousands of visitors, while other gained thousands.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin
Thinking about it, we should be more concerned about the stats of our website goals such as earnings or new subscribers. Web site traffic can be flattering but ultimately worthless unless it converts to our goals. For example, much of our traffic could be from content-scraping bots. If that traffic reduced by half it would be a good thing maybe (unless you benefit by having your content scraped)?