The State of League Parity

With players and team personnel reporting to their spring camps, the 2023 season is almost upon us, with 30 teams set to play over 2,000 games in an effort to qualify just for a chance to reach the ultimate goal of a World Series. It’s a marathon of unparalleled scale in American professional sports, and when all is said and done, some of those teams may be separated by as little as one or two wins — or, though it hasn’t happened since the tragic assassination of Game 163 last winter, any of a series of tiebreakers buried somewhere in the season standings.
That such a long race can come down to the final days is part of what makes our sport brilliant, like some amplified version of Monday’s UAE Tour cycling photo finish my colleague Michael Baumann shared on Twitter. It is part of what makes us all tune in so faithfully for this marathon; over a long summer, the margins between the playoff-bound and the homebound can be paper thin. Just ask last year’s 87-win Phillies and 86-win Brewers, who finished their seasons with extremely different tastes in their mouths.
All this to say: competitive balance is, well, a delicate balance, and with the debut of our 2023 playoff odds last week, there’s no time like the present to evaluate the state of the league from a parity perspective. Competitive parity in MLB has been a hot topic for the better part of a decade as we’ve started to see megateams like the Dodgers and Astros routinely eclipsing 100 wins, and others getting more comfortable with finishing somewhere around 60. In the five full seasons since 2017, 17 teams have reached 100 victories; just five did so in the previous 11 years. On the other side of the standings, prior to 2019, there had been just one season in which as many as four teams lost 100 games; then four clubs did so in each of the 2019, ’21, and ’22 seasons. With that in mind, here’s a look at the disparity in team winning percentage at the end of each season since 1960:
A few things are clear: measures of parity are pretty susceptible to swings in either direction, and as for right now, we are playing through a particularly disparate era. After a seven-year low in 2014, disparity spiked over the next five years to a peak standard deviation of .098 in 2019 before effectively leveling out around .090 in the last three. Left unchecked, this could pose a risk to the delicate balance of maintaining an exciting and marketable 162-game regular season. A wider spread means fewer tight playoff races and more teams with known playoff fates in the latter months of the regular season. Read the rest of this entry »