This page explains how Derrick Cone (USATT# 64672)'s rating went from 1991 to 1987 at the Valley of the Sun held on - 6 Dec 2009. The links below take you to pages that describe various aspects of the rating processor.

The rating processor goes through 4 passes in order. The links take you to pages that provide detailed explanations of the calculations during each of the 4 passes.