It is more elaborate than that. There are a lot of measurements and mass is quite important as are all the tine lengths. For a "typical" buck like mine, symmetry is important because only the weak side measurement actually counts in the official net score, but there is also a gross score which is the number of inches before deductions. For "atypical" antlers, I think there are no deductions, so it is easier to get a higher score for a smaller rack. Below is the scoring sheet for a typical rack. My buck will not score well.
http://www.dnr.sc.gov/wildlife/deer/pdf/ScoreSheet.pdf
