2025 Season Inequality: Analysis & Predictions

Translated by Marco Gámez

In 2017 I introduced the Gini coefficient. Well, I introduced it to some of you; others already knew him. The Gini coefficient, invented by Italian statistician Corrado Gini, measures inequality within a distribution. Gini created this measure to assess income or wealth inequality. The Gini coefficient ranges from 0 (perfect equality) to 1 (perfect inequality). Here is a standard real analysis prepared by the Luxembourg Income Study and processed by publication Our World in Data. It shows the Gini coefficient of countries’ disposable income (using the most recent year since 2021) after taxes and transfers (direct payments from the government to people), that is, income inequality:

The Gini coefficient is approximately equal to half the expected difference between the incomes of two randomly chosen citizens. As can be seen in the graph, the Czech Republic, with a gap of 49% in 2023, was the most equal country. The most stratified was Colombia, with a difference of 102% in 2023. The United States, with 79% in 2024, ranks sixth.

In the article I linked to above, I used the Gini coefficient to measure the inequality among Major League players in home runs hit and stolen bases. I daresay this was not what Gini had in mind when he devised his metric in 1912, even though Ty Cobb y Bob Becher They each stole more than 80 bases in 1911. But hey, it worked, even if the use was a bit forced.

Here’s a use that’s less so: won-loss records. Yes, they are not the same as wealth or income. But we can compare teams’ winning percentages in a given season on a level playing field, since they all play roughly the same number of games, which is easier than comparing home run totals between a player with 700 plate appearances and another with 70.

Eight years ago, I calculated Gini coefficients for each season, separated by league, from 1901 (the year the American League was established) through 2017. I have updated this analysis in 2018, 2019, 2020, 2021, 2022, 2023, and 2024. Now let’s go to 2025.

Before showing you the results, let’s establish a frame of reference. In a 12-team league, if everyone finishes 81-81, the Gini coefficient is 0.00: perfect equality. If one team wins 92 games, another wins 90, another 88, and so on until one wins 70, the Gini coefficient still rates it as fairly equal: 0.05. If half the teams finish 162-0 and the other half 0-162 (I know that’s impossible, but play along with me), the Gini coefficient would be 0.50: clear inequality, although not at the level of total inequality (not even at the level of Colombia).

Over the past 125 years, the leagues’ Gini coefficient has ranged from a low of 0.048 to a high of 0.168.

Here is the most lopsided league in MLB history: the 1909 American League.

This is what a Gini coefficient of 0.17 looks like in baseball. The Tigers, Athletics and Red Sox accounted for almost half of all the league’s victories. Nobody else was good, and the Senators were so bad you wanted to cover your eyes.

This type of situation occurred frequently in the early years of baseball. Of the 12 most unequal leagues since 1901, that is, 250 league seasons, the only one after World War II is the 1954 American League (the fourth most unequal; Cleveland won 111 games, New York 103, Chicago 94, and no other team even reached 70 wins).

In contrast, the only year before World War II among the 22 most equal seasons according to the Gini coefficient was the 1915 National League, weakened by the Federal League (which disappeared after that season).

The most equal league in history was just 11 years ago:

Of course, that’s not how it worked in the American League during 2015. There were three divisions, and the Royals won theirs by 12 games and the Blue Jays won theirs by 6. But, for the league as a whole…those teams were pretty even. The difference between the first-place team and the 15th-place team in 2015 was smaller than the distance between first and sixth place in the most lopsided season of all time, the 1909 American League. The Gini coefficient for the 2015 American League was 0.048. The 1974 and 2015 American League seasons, along with the 1915, 1968, and 1983 National League seasons, are the only major league seasons with a Gini coefficient less than 0.05.

Where is the recently concluded 2025 season located? For one thing, the Brewers led the major leagues with 97 wins, the lowest total for MLB’s top team since 2013. That suggests a narrow gap between the teams. On the other hand, the Rockies lost 119 games, the White Sox 102, and four other teams lost at least 90. While there were no super teams at the top, there were some really bad ones at the bottom.

The Gini coefficient of winning and losing percentages in the American League was 0.064. In the National League it was 0.086. The American League figure was the lowest in the league since the aforementioned 2015 season. Both the American League and the National League are low in a historical context.

• In the 250 Major League seasons since 1901, the American League’s inequality was the 29th lowest of all, at just the 12th percentile. The National League’s figure was also below average, at 113th, corresponding to the 45th percentile.
• In the 160 Major League seasons since 1946 (end of World War II), the American League’s inequality was the 26th lowest (16th percentile) and the National League’s inequality was the 64th (40th percentile).
• In the 114 Major League seasons since 1969 (with the advent of divisions), the American League’s inequality ranks 94th (18th percentile) and the National League’s inequality ranks 79th (31st percentile).

Here are the fifteen most lopsided seasons of the Divisional Era.

The 1977 American League and 1993 National League were expansion years, as was 1969. (The 1998 expansion Rays and Diamondbacks are not listed.) The 2020 season was, well, you know. The level of inequality that we have seen in several years of this century is worse than that of most expansion seasons and that of the year of the pandemic.

But that inequality has been greatly reduced recently. The National League went from being one of the most unequal of the Divisional Era in 2021-22 to being more equal than usual in the last three years. Inequality in the American League fell sharply in 2024 and declined further last year. Inequality in baseball is more volatile than national income, but we appear to be trending away from recent peaks.

Maybe we are seeing more parity, or more mediocrity, depending on your point of view. But if the argument for a salary cap, of which we will hear a lot this year, is based on a supposed lack of competitive balance, it has no empirical basis. (And the same is true if it is based on a lack of ability to climb the leaderboard or to qualify for the postseason).