This page explains how David Trykall (USATT# 73055)'s rating went from 1641 to 1615 at the 2009 Indiana State Closed Cham held on - 19 Apr 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.