Offense is down throughout Major League Baseball this season. For the first time since 2015, there was less than one home run hit per team, per game, for the month of April:

2022: 0.91

2021: 1.14

2019: 1.31

2018: 1.09

2017: 1.17

2016: 1.05

2015: 0.91

A number of factors are responsible for the reduction in home runs, and one of those factors involves how baseballs are being stored. During the 2021 season, 10 teams around the league stored their baseballs in humidors. This season, in 2022, all 30 teams are storing their baseballs in humidors.

Humidors are climate-controlled chambers that emulate the boxes used to preserve cigars. Humidors ensure baseballs are stored at average humidity. In places like Colorado and Arizona, where the parks are notoriously hitter-friendly, humidors prevent baseballs from drying out. This practice, therefore, helps pitchers, since dry baseballs have more bounce and can fly farther off the bat.

One would think the opposite effect would be true in the more humid ballparks, like Miami or Tampa Bay — that keeping the balls relatively dry would provide an advantage to the hitter. However, physics indicates that this is not the case. True, the dryer baseball would come off the bat at a faster rate. However, that lighter, dryer baseball would be flying into comparatively thick, humid air, which increases air resistance and slows the ball down.

The effect of humidors can be seen when comparing offensive numbers from 2021 to 2022 for teams that previously had humidors versus those for whom the humidor is a new addition this year.

Offensive numbers in the ballparks that already had humidors in 2021 look similar this season. However, in places where the humidor is debuting, offense is noticeably down around the league.

It does make sense that all 30 parks should be playing with the same baseballs, stored in similar conditions, as that can help preserve a more even playing field and reduce the varying effects of certain parks. This change could also be construed as a concession to pitchers, as humidors can make baseballs easier to grip.

Notably, the use of humidors isn’t the only change to the league’s baseballs this year. In response to the high home runs rates in recent seasons, tension was loosened on the first of three wool windings within the ball itself. Rawlings’ research prior to the start of the season estimated the adjustment would reduce the ball’s bounciness and also reduce the ball’s weight by 2.8 grams without changing its size. These changes were designed to lose one to two feet of distance on balls hit more than 375 feet.

It’s hard to tell with any definitiveness which of these factors is impacting offense more. It will be interesting to see how the season progresses, and whether offensive numbers remain consistently down through October.