I thought there had been discussion in the past about there being some sort of reason for being placed on position 10, and google bouncing you from 10th to second page, 11th but I couldnt find it.
I've been watching this go on for two pages I have that were once penalized (for what I believe to be over-optimization). Penalty ranged from not ranking, to ranking on page 6 to page 3. It was #1 for many years across most of it's targeted keywords.
But they've been doing this bounce for more than a few months, and I see certain newer pages of sites pop-up on page 1 (position 9) for the day then disappear, likely for their....what's the seo term...temporary new page/site boost.
Does anyone know if there is some sort of testing that google does for these types of positions for certain keywords? Maybe a trust check or a "time on page", "bounce rate" "whatever check" to see where it ultimately belongs?
It does seem like some kind of testing goes on - not bounce rate so much as click-through rate.
However, this phenomenon also involves "testing" for the sites that pop in above yours on the first page, the ones that cause your ranking to go to the second page. I often think it's more about "statistical tuning" for the SERP as a whole, more than it's about any one site on the page.