This page explains how Donald Duff (USATT# 18627)'s rating went from 1890 to 2089 at the 2005 N. American Teams Open Ch held on - 27 Nov 2005. 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.