This page explains how Sean Koster (USATT# 212045)'s rating went from 1591 to 1585 at the AZ PTTC Monday event from 16 Apr 2018. 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.