This page explains how Paul L. Nielsen (USATT# 8708)'s rating went from 1501 to 1500 at the 2021 Butterfly May Upside Down Tournament held on 15 May 2021 - 16 May 2021. 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.