This page explains how David Guan (USATT# 217271)'s rating went from 828 to 815 at the HCTT Tuesday Night League event from 19 Dec 2017. 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.