Shaddows - 3:58 pm on May 27, 2011 (gmt 0)
I interpret your results in a completely different way.
Assume for a moment that every site has traffic throttled to some degree. (I am personally convinced of this, but know others will dispute)
What it sounds to me is that your blocked content is being "virtually" placed in SERPs, taking your exposure-allocation for the day. However, it's not being actually shown, so the exposure-allocation does not convert to traffic-allocation.
To me, this is strongly suggestive that Google throttles exposure, not traffic.
I've always thought that traffic was throttled, and exposure was the tool they used to do that. If exposure is the metric, and traffic is incedental, that would be a fascinating result.