This page explains how Xiongxiong Zhuang (USATT# 1171978)'s rating went from 1944 to 1907 at the Butterfly Spin &Smash December Open held on 3 Dec 2021 - 5 Dec 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.