The overall score is not the average of all of the other scores.
The overall score listed in each review is a score given to the overall impression of the shoe. It takes into account things which are not scored in other sections so it is not an average of the other scores.
For instance, we do not score a shoe on how it looks. A shoe could feel great, but if a player can't stand the sight of his own feet every time he looks down, they could affect his overall score. Alternatively, the fashion diva might score his shoes higher overall if he just loves the way they look (I wont mention any names like Jason here, because I don't want anyone to think any of our testers are shallow).
Hope that helps,