I am looking at GA of a blog that has been gradually losing G traffic for the last 2 years. To me it looks like it went overboard with ads. At any given position on the page there are 3 ads displayed on the screen and in total there are aprox 11 ads per page.

I thought it's Panda slowly killing it, but then I found a sub-page that went up the SERPs 2 years ago and has kept the ranks since.

Panda is a sitewide penalty. By that the sub-page should have been losing ranks gradually as well, right? So if it kept its ranks throughout the last 2 years, then it's not sitewide penalty and it's not Panda. Right?

There is one other potential reason why ranks are gradually declining, but I need to rule out Panda first.