LeBron James of the Cleveland Cavaliers flexes his arm after making a free throw. (Jae C. Hong/AP)

Recent big-name changes in NBA rosters — LeBron James to the Lakers, DeMarcus Cousins to the Golden State Warriors, among others — have led commentators, including The Washington Post's Tim Bontemps, to note that the teams already rich in talent and money are getting even richer.

Some observers are warning that this “lopsidedness” has, in effect, “broken” the league. How are you supposed to have a competitive season if a small handful of teams have a virtual monopoly on the league's firepower?

But Bontemps shared some numbers earlier in the week that illustrated how the concentration of talent and power has always been part of the NBA: The Celtics and Lakers combined, for instance, have won 33 of the league titles awarded in the 72 years of the NBA's existence.

To us here at Wonkblog, that inequality in championships sounds a lot like the inequalities of wealth and income we write so much about. If we were to think of pro sports leagues as economies, with championship titles as economic resources distributed unevenly throughout those economies, that could allow us to answer a number of questions: How, for instance, does championship inequality in the NBA measure up against inequality in the other major sports leagues? And how do they all stack up measures of economic inequality in the U.S. economy?

To start, we tallied the total number of championship victories for each currently active franchise in each of the four major sports leagues — the NBA, the NHL, MLB and the NFL — since the leagues' inceptions. In cases where a team changed names or moved between cities, we tallied those victories under the modern-day iteration of that team. For example, the Oakland Athletics' nine World Series wins include five victories as the Philadelphia Athletics.

For better comparison across leagues we expressed the number of championship victories as a percentage of all championships awarded in the league's history. Here's what that looks like.

Sure enough, the NBA, NHL and MLB stand out for having high proportions of title wins concentrated among just one or two teams. In three leagues, the winningest teams have racked up over one-fifth of the leagues' respective championships. The NFL is an outlier in this regard, with the Steelers' six Super Bowl wins accounting for just a little over 10 percent of total Super Bowl victories.

One way to summarize these stats is to look at the percentage of all league championships won by the top 3 teams in each league. This is somewhat akin to looking at, say, the percent of all income held by the top 10 percent of wage earners.

In the NBA, the Celtics, Lakers and Warriors have combined to win about 55 percent of all 71 league championships. The chart for the NHL is similarly skewed toward the top of the distribution, with the Canadiens, Maple Leafs and Red Wings combining for over half of all Stanley Cup victories since 1915.

World Series Championships are somewhat less skewed, with the Yankees, Cardinals and Athletics combining for about 42 percent of wins since 1903. And the NFL is even less so, with the Steelers, Patriots and Cowboys accounting for just 31 percent of all Super Bowl wins.

Judging by the top three teams' share of championships, in other words, the NBA is the most unequal of the four major leagues, with the NHL not far behind. What this means, in effect, is that across their respective leagues' histories, the median MLB or NFL team has a somewhat better chance of going all the way in a given year than the median NBA or NHL team.

Another way to think of these numbers is in terms of the Gini coefficient, which measures how evenly resources are distributed in a society. For our purposes here, a radically egalitarian league where each time had won the exact same number of championships would have a Gini coefficient of zero, while a maximally unequal league where the same team won the title every single year would have a coefficient of one.

The Gini coefficient of NBA championships is 0.721, indicating a highly uneven distribution. The NHL stands at .706. The MLB and NFL, by contrast, are a little less than 0.6.

To put these numbers in context, the distribution of championships in the MLB and the NFL is similar to the distribution of household income in the United States as of 2016. NBA championships and Stanley Cup wins are even more unequally distributed, but not as unequal as household wealth, which has a whopping .877 Gini coefficient, according to NYU economist Edward N. Wolff.

One limitation of these numbers is that they aren't really sensitive to fluctuations over time. The NHL numbers, for instance, are highly influenced by the Montreal Canadiens' 24 Stanley Cup victories since 1915. But the Canadiens haven't won the cup since 1993. It's possible, in other words, that the post-1993 distribution of Stanley Cup wins is more (or less) equal than the distribution across the entire history.

Conversely in the NBA, the Golden State Warriors have won three out of the past four championships. We may be at a moment where NBA talent is even more concentrated than the Gini numbers suggest, effectively giving one team a lock on the title for the foreseeable future.

But these numbers do help us understand that the concentration of talent (and hence, league championships) in a small handful of teams seems to be a consistent feature of major league sports in the United States — just as the concentration of wealth and income has been a consistent feature of the U.S. economy.