This page explains how Zhizeng Sun (USATT# 88210)'s rating went from 1824 to 1820 at the 2021 HITTA Butterfly Fall Open held on 14 Aug 2021 - 15 Aug 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.