There are a few things to note when looking at these numbers. MLS has a much smaller average wage and a much smaller total wage sum than all the other leagues; the $226,464 average wage is less than the minimum salary of all the other leagues. Conversely, MLS has no official maximum wage, which differs from leagues like the NHL, NBA or NFL, where there is a max possible salary and a harder and harsher salary cap. Furthermore, the other four leagues are the apex of talent and competition in the world for these sports, while the most generous MLS fan would be hard pressed to argue that the league is in the top five soccer leagues in the world. Lastly, MLS is a league that continues to grow, entering 2015 with 20 teams. The NBA, NHL, and MLB all have 30 teams, and the NFL has 32. Perhaps MLS' comparatively small number of teams contributes to some of the difference. We could go on here, but these all essentially boil down to this: MLS doesn’t compare perfectly to the other American sports. But you already knew that.
That said, these are still the five major professional sports leagues in the US, and these are the leagues that we MLS fans are constantly measuring ourselves against. It’s also why this is still an interesting and valuable exercise.
In some areas, MLS falls in right among the other major sports, while in others it is a clear outlier. For instance, when dividing the average salary by the median salary across leagues, MLS is on par with the NFL and more equitable than MLB. This is one way to say that MLS salaries as a whole are not as skewed upwards as those of MLB. MLS’s major differences come in the income disparity at the extremes – those with the biggest salaries are simply making much more than those at the bottom, especially when compared to other leagues.
When an unheralded young player gets his first callup to the Majors, he is usually making around $500k, which is about 1/60th of the $30 million Clayton Kershaw will make in 2015. Similarly, the NBA has the highest average salary of any other league in the world (beating out the Indian Premier Cricket League. Who would have guessed?), and Kobe Bryant makes about 40 times the rookie minimum. While MLS has the shortest average career of the major sports at only about 2.5 years, the NFL is second shortest, and presumably comes with a more severe wear and tear on the body. In that league, Aaron Rodgers’ salary is 52 times the size of the league's lowest paid player. Kaka, the flashiest name on the roster of the newly promoted Orlando City, makes about $7 million per season, which is almost 200 times what players like Dylan Remick and Bradford Jamieson IV made last year. Indeed, Kaka alone made more than the 160 lowest paid players in MLS… combined, and he accounts for more than 5.5% of total league wages; next closest is the NBA where Bryant is at 1%.