This page explains how Gregg Robertshaw (USATT# 9501)'s rating went from 1999 to 2027 at the 2021 Butterfly Cup held on 3 Sep 2021 - 5 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.