Hello, Sam.
Your questions are pretty much answered here already -- being the scores a game comparison tool, I don't need to think about how the global score relates to the aspectual scores, although, given that the latter are essentially a breakdown of both, mechanics and aesthetics, coincidence, to a point, should come off naturally.
I had made up my mind about getting rid of this score system for Postback 2.0 in favour of the more universally accepted 1-to-5 overall scale, but you people are really making me think otherwise thanks to this silly controversy.