Surely the question is if the green pixels are Googles' measure of a pages importance, why have so many pages that don't appear to have lost SERPs dropped so dramatically in TBPR. Like everyone else, I've noticed some really huge drops - so Google is trying to stop people selling links based on PR value if they don't tow the line on rel=nofollow. What really baffles me is just how they managed this via an algorithmic method - the idea that they reviewed the entire internet "by hand" is obviously an impossibility so now we're all going to be fighting a new battle working out whether Google thinks we have been paid for outbounds whether we have or not.