If you have ads. above the 'fold' on your site that are considered excessive it takes a lot of scrolling to get at your content, then your site may get demoted by Google.
So if your page is full of blocks of ads, pushing your 'light' content further down the page, it does not make for a user friendly site and will be going down in rank.
Google have announced:-
"This algorithmic change does not affect sites who place ads above-the-fold to a normal degree, but affects sites that go much further to load the top of the page with ads to an excessive degree or that make it hard to find the actual original content on the page. This new algorithmic improvement tends to impact sites where there is only a small amount of visible content above-the-fold or relevant content is persistently pushed down by large blocks of ads."
I see too many sites like this and it does not help people looking for information, which is what the internet is about after all.
Serve up relevant content, well written, and informative on a regular basis and people will come back for more information.
Your pages do change - don't they?