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The Potential Importance Of Humidors In Major League Baseball

This season, Major League Baseball is requiring teams to store baseballs in an air conditioned enclosed space but will humidors soon become league-mandated?


Over the course of the Major League Baseball regular season, teams go through approximately 260,000 baseballs, which equates to about nine to 10 dozen per contest.  Balls are produced on a massive scale and often spend months just sitting in the box, before being prepped by rubbing mud on it, and have long been stored at the discretion of each individual team, leading to variances in the baseball’s flight.

But over the last two decades, storage has become important and is now leading to significant changes.

When the Colorado Rockies became MLB’s newest expansion team back in 1993, many speculated how the air quality of a stadium more than a mile above sea level would affect the game.  Before long, the league realized the abundantly dry Colorado air at Coors Field impacted how baseballs carried, leading to offensive onslaughts with a great deal of regularity.  In 2002, engineers at the Denver-based ballpark installed a humidor for storing game balls, in an attempt to limit the heavy hitter’s advantage – and the results were telling.  See, the humidor provides a specific amount of moisture to the baseball, making it slightly heavier and thus slowing down the ball in the dry air, so players are unable to hit it as hard.

According to Popular Science, from the 1995 to 2001 seasons, before the humidor was installed, National League pitchers at Coors Field had a terribly high earned-run average (ERA) of 6.50, more than two points higher than the 4.37 ERA at other stadiums.  After the humidor was installed, from the 2002 to 2008 season, N.L. pitchers posted a much lower 5.46 ERA.  Some think it’s nothing more than a coincidence, however there’s validity in how baseballs are stored and Major League Baseball continues to explore the science behind the humidor and its impact in other markets, such as Arizona.

Earlier this year, it was announced that this season, for the first time ever, the league would require teams to store the balls in “an air conditioned and enclosed room” as it continues to substantiate data.  But Chase Field, the home of the Arizona Diamondbacks, decided to be the second franchise to incorporate a humidor for baseball storage.  Widely speculated for quite some time, thanks to its success at Coors Field, a humidor was constructed to combat the wickedly dry desert air.  The team stores the baseballs at the league recommendations of 70 degrees and 50 percent humidity.  Much like Colorado, the goal was to transform Chase Field from a hitter’s park to a pitcher’s park, limiting the runs scored and the hitter’s advantage.  In 2017, there were 803 runs scored at the ballpark – an average of 9.91 runs per game, which was eighth in MLB.  Through 40 games at Chase Field this season, there have been 77 fewer runs scored by the Diamondbacks, which have also allowed 11 fewer runs than at this exact point last season.  While it’s still too early to know the full extent the humidor will play in Arizona, MLB is considering it as a viable option and it could eventually become mandated league-wide.

Depending on the data gathered this season, it could be required in every park as early as 2019.  But what about cities that are traditionally high in humidity, like San Francisco’s AT&T Park for instance?

During the month of July, the average humidity in San Francisco is 78 percent, which means a humidor might actually make the ball lighter and while there’s still wind and other varying factors, it could have a huge effect on ball dynamics in general.  With the majority of ballparks experiencing over 50 percent humidity, home runs could potentially increase significantly.  As McCovey Chronicles recently noted, the humidor has the potential to make San Francisco a desirable destination,  since the lighter ball, which would be stored at a lower humidity, could travel farther thanks to exit velocity providing more momentum.  This would be the case at many MLB stadiums, ones where the dimensions are already quite favorable for the hitter.

There’s still a variety of angles that have to be considered but what exactly is MLB’s end result here – doesn’t more scoring bring more eyes to the game?  Sure, more runs make the game more marketable but, in a perfect world, the hope is that the ball carries the same way no matter what city – a baseball will travel at the same rate in Seattle as it would in Milwaukee, Houston or Philadelphia.  Humidors would simply create a standardization around the league, allowing pitcher’s like Justin Verlander – who recently complained that baseballs were slick, causing inconsistent breaking balls – a chance to better face off against hitters.  In a league that continues to transition to favor the hitters, this could be a substantial step in reviving small ball.

Only time will tell, as more data is being collected each and every night this summer.