This page explains how Ruichen Xiao (USATT# 217212)'s rating went from 819 to 821 at the Spttc Saturday Night League event from 25 May 2019. 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.