USA Methodology

The Basics

How are initial Elo ratings determined?

All leagues based in the United States are assumed to be independent of one another, so each league's average Elo rating among all active teams held constant at 1500 throughout every season. For each league, our simulations begin with a defined starting season, typically the first in the modern era (e.g. 1901 for MLB, 1933 for the NFL). At the beginning of that season, all active teams are assigned an initial Elo rating of 1500. We assume no prior knowledge about team strength, even if a team existed before the simulation begins. As a result, strong franchises like the 1901 Pittsburgh Pirates often begin underrated, while weaker teams such as the 1901 Cincinnati Reds may appear overrated at first.

Expansion teams are assigned an Elo rating based on how a roster comprised of replacement-level players would be expected to perform in that league. Teams absorbed from other leagues (e.g. Cleveland Browns or Edmonton Oilers) retain their ratings from their previous league to reflect known performance.

The table below summarizes the range of seasons covered for each league (both active and defunct) included in our simulations, along with the initial Elo rating assigned to expansion teams.

How are Elo ratings adjusted for the beginning of the following season?

Due to roster turnover, coaching changes, and other offseason variability, we never assume that a team's Elo rating at the end of one season carries over unchanged to the next season. Thus, each team's rating is regressed towards 1500 by some percentage. The degree of regression depends on how highly correlated the standings were between the two seasons and is specific to each league and season.

When teams join or leave the league - through expansion, contraction, or disbandment - the Elo ratings of the remaining teams are further adjusted by a constant amount to keep the league-wide average at 1500.

How are ties handled?

When a game ends in a tie, the team with the higher Elo rating will lose a small number of points, while the lower-rated team gains an equal amount. Although it may seem counterintuitive for Elo ratings to change after a tie, this logic is based on expectations. If a weaker team holds a stronger team to a draw, it has overperformed and should be rewarded slightly. Conversely, the stronger team in that matchup has underperformed and should be penalized for playing below expectations.

How is a team's personnel taken into consideration?

In short, it isn't - at least not in most situations. Because the primary goal of this site is to understand how a season would have played out historically, we don't attempt to incorporate every starting pitcher, quarterback, goalie, injury, or trade into a team's Elo rating. Doing so would require not only tracking personnel changes in every game, but also estimating their impact at each point in their career. This would be a monumental task full of speculation and variability. Instead, we assume that a team's Elo rating reflects its overall strength regardless of specific personnel.

The one exception is in the NFL, where Elo ratings fluctuate more rapidly than in other sports due to the short season. In games where at least one team has clinched a playoff spot and is locked into a seed, we reduce the Elo adjustment by two-thirds. This accounts for teams sitting their starters for most or all of the game, which can lead to extreme outcomes.

How are cancelled games handled?

Any games that were cancelled due to extenuating circumstances (usually weather) were added back into the simulation schedule on their original dates to ensure every scheduled game is simulated. Otherwise, teams would play an uneven number of games in each simulation. Each team's Elo rating on the originally scheduled game day is used to calculate win probabilities. However, Elo ratings are not updated after these simulated games since no actual results exist.

What about strike-shortened seasons?

Each strike-shortened season was handled slightly differently depending on the circumstances:

• 1972 MLB Strike: All cancelled games were added back into the schedule on their originally scheduled dates.
• 1981 MLB Strike: All cancelled games were added back into the schedule on their originally scheduled dates. Instead of separating the season into halves, the top two teams by record in each division made the playoffs in the simulation.
• 1994 MLB Strike: All cancelled games were added back into the schedule on their originally scheduled dates.
• 1995 MLB Strike: Schedule as originally played with 144 games per team was used.
• 1982 NFL Strike: Schedule as originally played with 9 games per team was used. 16-team playoff format was retained in the simulation.
• 1987 NFL Strike: Schedule as originally played with 15 games per team was used.
• 1994-95 NHL Lockout: Schedule as originally played with 48 games per team was used.
• 2004-05 NHL Lockout: Season not simulated.
• 2012-13 NHL Lockout: Schedule as originally played with 48 games per team was used.
• 1998-99 NBA Lockout: Schedule as originally played with 50 games per team was used.
• 2011-12 NBA Lockout: Schedule as originally played with 66 games per team was used.

How were the leagues interrupted mid-season by the COVID pandemic handled?

All cancelled games in the NHL and NBA were added back into the schedule on their originally scheduled dates.

In the NHL, all cancelled regular season games were simulated. The normal playoff format was used in the simulation with the top three teams in each division qualifying along with the next two highest point totals among 4th and 5th place teams in the conference.

In the NBA, all regular season seeding games played in the bubble were counted towards the regular season standings on the date they were actually played. The normal playoff format with the top 8 teams from each conference qualifying was used with no play-in games.