One of my sites' ad units (not all but just 2) saw a massive drop in pageviews. BUt when i check traffic to my site, nothing has changed significantly. This happened about 4 days ago and has remained like that. What could be wrong???
Traffic gone to zero today? Sadly I have been informed that this has occurred due to http://searchengineland.com/too-man...-penalized-by-googles-page-layout-algo-108613 If you like me have ads above the fold then read the link then buy a shotgun or a rope.
The article in searchengineland doesn't really apply to the OP, since his traffic (I suppose as seen in analytics or some other tool) hasn't dropped, but only the reported ad impressions in adsense admin.. Once again Matt Cutts talks to say nothing specific.. How much is too much? Well you'll never know.
Have any changes happened realted to your traffic sources? Maybe traffic is the same, but more is coming from different places that are lower quality?