This page explains how Sumin Lee (USATT# 91475)'s rating went from 1846 to 1820 at the Westchester 2021 September Open held on 25 Sep 2021 - 26 Sep 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.