This page explains how Peter Cao (USATT# 219413)'s rating went from 1519 to 1459 at the LATTA Butterfly Open September 2021 held on 25 Sep 2021 - 25 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.