Tools for calculating and visualizing Elo-like ratings of MLB teams using Retosheet data

BaseballRatings

This project uses historical baseball games data to calculate an Elo-like rating for MLB teams based on regular season match ups. The Elo rating system was originally developed for ranking chess players but also can

Wikipedia has more technical details on the rating system: https://en.m.wikipedia.org/wiki/Elo_rating_system

A similar analysis was done by 538: https://projects.fivethirtyeight.com/complete-history-of-mlb/

This repo consists of three primary pieces of code:

Parser.py imports and cleans the game-level data. It performs basic calculations, such as determining game winners.
Elo.py calculates Elo ratings for a given set of games data
Visualization.R plots the output in a variety of interesting ways

Data

Source: https://www.retrosheet.org/gamelogs/index.html

This data was compiled by Retosheet.org. The only stipulation for use of this data is prominent display of this statement:

The information used here was obtained free of
charge from and is copyrighted by Retrosheet. Interested
parties may contact Retrosheet at "www.retrosheet.org".

The formats of the data can be found in the Formats.py module.

Examples

This graph shows the distribution of each team's Elo rating over the course of the decade 2010-2019. The ratings are weighted by in-season days.

RatingDistr

This graph shows the progress of the 5 teams in the AL West over the 5-year period starting in 2014.

RatingsALW

Each team was also ranked by their Elo relative to the rest of the league on each day. The graph below shows the time spent at each rating for the 5 teams in the AL West.

Rankings