May Update Advice Needed

Anyone have any theories on they update? I had 3 sites drop all keywords and traffic after previously being ranked on page 1 for several key terms. Been testing to see why they were hit but still at a loss.

My other sites started around the same time that were not hit has about the same mix of content and links so thinking it was not content or links. Some of the sites were in the same niche so does not seem to be related to broad category.

Just checking if anyone has some theories that maybe I could try to test. Thanks

Do you have an affiliate site?
According to my observations, one of the key factors now is branded traffic, sites with branded traffic are not affected.

Dmytros said:

Do you have an affiliate site?
According to my observations, one of the key factors now is branded traffic, sites with branded traffic are not affected.

Click to expand...

There was a separate thread on BHW explaining what types of blogs got affected. In brief, those with very good content are not affected.

I had some pages hit by the May update (first time ever hit by an update) and I would like to think it's a content related hit.
But I can't really figure out what part of content.

Same here. I've seen only a few sites that have actually recovered from May update, and the biggest pattern I see is, they remove a lot of content, and then IDK if they improve it or not, but they do constant publishing after that. But my main question was how do they know which content to remove off site?