My eCPM is extra low today - about half of a low day. It's an odd trend - views are up this week, clicks are up, affiliate sales are up, but eCPM is down.
When there's a low eCPM even though views and clicks are up, I can't really attribute it to ad irrelevance issues. But I can think of a few reasons why (aside from the "stats stuck" theory):
1) smart pricing, or
2) The traffic is somehow of a different quality. I get mostly organic traffic, but maybe it's not as targeted as before, and maybe the clicks are on personalized ads rather than content based. Or
3) the new Modified Broad Match in AdWords somehow changing things. Not sure how, because I don't understand it, but anything seems possible...