Elo Ratings they are most often used incorrectly. This article presents important details that will help you find the best possible NFL Elo ratings for determining NFL point spreads and power rankings.
NFL Elo Ratings
NFL football is the most popular sport in America today. Fans want to know which teams are the best, and win-loss records can be misleading. A team with a 6-2 record in a weak division may not be better than a team with a 4-4 record in a strong division.
Many NFL web sites contain power rankings, which often reflect a lot of statistical information. But power rankings may also contain the author's personal preferences or they may simply reflect conventional wisdom. Fans may want to know which team is going to win, to predict the score so they can win that office betting pool, or they may want to try to beat the NFL point spreads.
Betting Spreads and Elo Ratings
Elo Ratings were developed by Hungarian mathematician Arpad Elo to rank chess players. The system also works for NFL games. But there's a huge difference between chess and American football. So football ratings and chess ratings have to be calculated differently.
There are four important differences between chess ratings and NFL ratings. You should be aware of these differences if you're looking at someone's NFL Elo ratings.
1. A chess game is a single head-to-head competition between two players. But football pits each team's offense against the other team's defense. So it is like two games in one. A chess player has a single rating, but an NFL team should have two ratings -- one for offense and another for defense. Some teams may have a very strong offense and a weak defense, so they will score many points but they will also allow a lot of points. The NFL Elo system can predict this when two separate ratings are used. So look for a system that provides you with two separate numbers. (To obtain a team's overall Elo rating, you can just average the offensive and defensive ratings.)
2. A chess game can only end as a win, loss or draw. Arpad Elo simplified his system by rating a win as 100% success, a draw as 50% success and a loss as 0% success. In the NFL, there is a big difference between a 21-20 victory vs. a 50-0 victory. In football, 50 points should be rated as 100% success, 20.5 points as 50% and 0 points as 0% success. There are several ways to do that. You can get a lot more information about a game when you use percentiles. So look for NFL Elo ratings that aren't based simply on wins and losses.
3. An NFL season is remarkable for its small number of games. There are only 16 games in the regular season, and three or four in the playoffs. But Elo chess ratings aren't very accurate for the first 25 games. Elo built a number called a "K-factor" and he set it to a low number (10 or 16) to prevent the ratings from jumping around too much. For NFL Elo ratings, you have to set the K-factor higher.
You can also re-run the ratings more than once, to get more stable numbers. So look for Elo ratings that are based on a higher K-factor, and find out as much as you can about how they are being used. Were they run more than once? If last year's rating used to begin the season, then it can help in rating the early games.
4. Elo ratings have always been a brilliant system for producing rankings. A chess player with a higher Elo rating is nearly always better than a lower-rated player. (Even if they have never played each other and have few common opponents.) And in chess, that's pretty much all they are used for. But in the NFL, they can also be used to predict:
- the final score of a game.
- one team's percentage likelihood of beating another.
- either team's chance of covering the betting spread.
- accurate power rankings for teams, and for offenses and defenses.
But if NFL Elo ratings are not being used correctly, then they can't really do any of these things accurately. But if they are being used accurately, then they are one very powerful tool for doing all this things and more.
NFL Point Spreads and Power Rankings
There is a lot of uncertainty when you try to predict the outcome of NFL games, and Elo ratings are not perfect. They may not be able to account for factors such as injuries or individual match-ups. If you are trying to figure out what will happen on Sunday, then be sure to take as many factors into account as you can.
If you see Elo ratings, then find out as much as you can about how they are calculated, based on the advice in this article. And if you can manage to find accurate NFL Elo ratings, then definitely make sure you take them into account when calculating point spreads and power rankings.
Erik Zoltan - Erik Zoltan has more than 20 years of computing experience working for large and small corporations such as ESI Technology, EDS, Inc. and ...
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