With the utmost respect for your expertise and knowledge, I have to ask.. Are you positive this is not a glitch in the system somewhere? The mathematical improbabilities of this happening are getting very large.
Double posting just because I've been staring at this for so long that I'm actually feeling like I'm going through depression. But thinking more clearly:
Just a few days ago, we had some VERY good luck. A day or two before that, we had almost 20 hours straight of having shifts end between 10 and 60% above PPS. Absolutely NOTHING has changed on the servers since that time aside from rolling the one server (which only has ~7% of the pool speed) back to 0.8.1 from 0.8.2. So for it to be a software glitch causing the unusual bad luck we're having right now, you would have to expect that we should have had -even better- than that luck just a few days ago.