I'm having similar problems with an adsense only site. Compared to the same period in 2010, April 1 - 21, the situation in 2011 looks like this:
Page views +49%
In 2010 nearly all ads shown were relevant to the content on the page. However, this year they are mostly irrelevant to the content, yet blocking them for 3 days and allowing relevant ads to take their place resulted in a signifcant drop in earnings. Thus I had no choice but to unblock them.