Indeed, I am not expecting compensation for the blocks that fail for me. Nor would I expect BB to be responsible for compensating folks when blocks do fail; agreed that is a rather onerous prospect.
To play devil's advocate for a moment with my Computer Science hat on for a moment, one would hope that BB has logs and the ability to parse those logs to precisely determine this kind of information quickly and easily. Sawzall (
http://research.google.com/archive/sawzall.html), for one example.
Back to blocking: It's a multi-faceted issue for sure, but in my mind official support for the ability to perform blocking (one general taking away a camp's aggro range during an attack to allow other generals to pass by) is separate from the support for specific blocks (and compensation when they fail). This is something that could be called out explicitly in an official statement, should BB choose to go this route.