This page explains how Daniel L. Koscielski (USATT# 60887)'s rating went from 1223 to 1221 at the US Open held on - 4 Jul 2004. 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.