This page explains how Adam Fan (USATT# 217518)'s rating went from 1899 to 1880 at the Westchester December2023 Open held on 29 Dec 2023 - 30 Dec 2023. 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.