Elo Rating Updates

30 Jul , 2018,
jcs
32 comments

We detailed our intentions to add some alternate rating systems for comparison in a previous post.

We got several comments and questions about this, with two common questions being:

1 – I thought the system in use was a version of Elo?

2 – What’s the point of adding alternate rating systems?

Addressing #1, the current rating system does share a few things with Elo, most notably, the core formula that manages the movement.  However, it has also borrowed elements from the Glicko rating system and has tons and tons of additional code in place to make it better equipped for MMA, which is still a very disorganized and unpredictable sport, in terms of not only the matches but the matchmaking as well.  Systems like Elo and Glicko were made for chess, a sport (game?) where competitors can play dozens of matches in a month where none of them get kicked in the head by their opponent.

So, if Elo wasn’t made for chess, what’s the point of including it?  Good question.  The standard system in place here has reached maturity.  Other than maintenance and bug fixes, it is what it is.  Furthermore, it is far beyond mathematics, it is essentially a software program due to the complexity.  Elo is mathematically pure and that’s what makes it so interesting.  It is also a new challenge — trying to tweak the available parameters while still keeping the formulas that govern the movement as pure as possible… plus it is something new to do and a new addition to the site.  The standard system is driven mainly by subjectivity, while using objectivity to help tweak new parameters so they aren’t simply arbitrary updates.  The Elo systems we add will be solely driven by objectivity.

I thought I’d post some updates as well.  I’m working on two versions of Elo:

“Standard” Elo

The standard version looks at the overall prediction rate for all fights in the database.

  • Starter rating is 1000.
  • K-Factor is 170.
  • Uses the standard “algorithm of 400” Elo equation.
  • Draws have a match impact of 0.5 for each fighter. Wins have a match impact of 1.0 for the winner, 0.0 for the loser.

 

“Modified” Elo

The “modified” version (which I may rename), looks at the overall prediction rate for all fights in the database, unless the fight results in a DQ, 1-round technical draw or includes a fighter with 2 or less prior pro fights.

  • Starter rating is 1000.
  • K-Factor is 275 for fighters in their first three fights, 155 for everyone else.
  • Uses the standard “algorithm of 400” Elo equation.
  • Fighter that holds a continent-level home advantage is given a 15-point adjustment in the core formula.  Ratings must be treated as “neutral ground”.
  • Draws have a match impact of 0.5 for each fighter.  Split decisions have a 0.67 for the winner, 0.33 for the loser.  Majority decisions have a 0.833 for the winner, 0.167 for the loser.  Other wins have a match impact of 1.0 for the winner, 0.0 for the loser.
  • Disqualifications and 1-round technical draws are ignored.

 

An Elo disclaimer, at least for the time being, is you need to realize that fighters’ reached their ratings based on their fight history and when comparing two fighters, their histories need to be similar.  In other words, it is realistic to compare TJ Dillashaw’s rating to Cody Garbrandt’s , because they are on “the same level” in terms of caliber, fight in the same era, same country in the same division.  It is not realistic to compare Demetrious Johnson’s rating to Bas Rutten’s, for obvious reasons.

 

 

Standard Elo – Top 10 – Active Men / Women

2446 Georges St. Pierre
2402 Daniel Cormier
2367 Jon Jones
2342 Tyron Woodley
2329 Robert Whittaker
2319 Max Holloway
2256 Tony Ferguson
2254 Khabib Nurmagomedov
2239 Ryan Bader
2236 Gegard Mousasi

 

1906 Amanda Nunes
1881 Cristiane Justino
1833 Rose Namajunas
1772 Jessica Andrade
1731 Joanna Jedrzejczyk
1705 Claudia Gadelha
1674 Karolina Kowalkiewicz
1671 Katlyn Chookagian
1664 Valentina Shevchenko
1659 Tatiana Suarez

 

Modified Elo – Top 10 – Active Men / Women

2357 Daniel Cormier
2353 Jon Jones
2343 Georges St. Pierre
2280 Max Holloway
2242 Robert Whittaker
2242 Tyron Woodley
2230 Gegard Mousasi
2215 Khabib Nurmagomedov
2194 Tony Ferguson
2178 Stipe Miocic

 

1887 Cristiane Justino
1854 Amanda Nunes
1826 Rose Namajunas
1762 Jessica Andrade
1735 Joanna Jedrzejczyk
1697 Valentina Shevchenko
1683 Livia Renata Souza
1677 Tatiana Suarez
1661 Claudia Gadelha
1658 Katlyn Chookagian

 


share this page