Arizona Diamondbacks’ Humidor Likely to Reduce Home Runs Significantly
The Arizona Diamondbacks are adding a humidor at Chase Field to help pitchers get a better grip on the baseball and it will likely reduce home runs significantly.
The famous humidor that was installed in Coors Field in Denver in 2002 is getting some company in the major leagues. The Arizona Diamondbacks announced plans to install a humidor of their own sometime this season, hopefully within the next month and before the Arizona summer hits with full force like a blast to the face from a heat furnace.
Diamondbacks president and CEO Derrick Hall said the team has discussed the use of a humidor for five or six years. He said, “We talked to former pitchers, whether it’s J.J. Putz or pitchers who have retired or pitchers we’ve traded, and said, ‘what did you like, what didn’t you like?’ They all talk about the grip.”
According to Hall, a study by MLB suggested that baseballs should be stored at 70 degrees and roughly 50 percent relative humidity. Hall claimed that was impossible to do in the dry summer months in Phoenix because he apparently never heard of air conditioning before the humidor idea occurred to him.
Chase Field in Arizona has been one of the best hitters parks in baseball during its existence. Not only is the weather warmer and less humid in Phoenix (it’s a dry heat, like hell) than in many major league cities, the ballpark is also the second highest above sea level, after Coors Field in Colorado. Coors Field, as every baseball fan knows, is routinely the best hitters park in baseball. It has an elevation of 5,211 feet above sea level. Chase Field comes in at 1,059 feet.
Hall claimed, incredulously, that the team doesn’t know if adding a humidor in Chase Field will suppress offense. He said, “The one thing you don’t really want to do is negatively impact the offense, because that’s part of the fun of Chase Field or Coors Field, but I don’t think it really did diminish the offense at Coors Field. We don’t know if it’s going to make much of a difference, but it’s probably a necessity.”
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It’s hard to know if Hall is serious with this quote. There is an abundance of information out there on the effect of the humidor at Coors Field. Surely, Derrick Hall has access to Google. As the president and CEO of an MLB team, Hall must have looked at studies that predict exactly how a humidor will affect offense at Chase Field. In this age of MLB front offices analyzing data more than they ever have in the past, Hall can’t really be this ignorant. It’s likely this is just public relations nonsense.
In fact, six years ago Professor Emeritus of Physics Alan Nathan wrote about home runs and humidors at Baseball Prospectus. In this article, he specifically mentioned that Arizona was considering installing a humidor. He used a model to predict that using a humidor at Coors Field would result in a reduction of home runs by 27.5 percent, plus or minus 4.3 percent (this was added in the comments of the original article). The actual reduction was 25 percent. As he wrote, “The closeness of the calculation to the actual result suggests that it is very plausible that the reduction in home runs at Coors Field can be attributed to the humidor.”
Nathan did a similar analysis to predict the reduction in home runs that would occur with the addition of a humidor at Chase Field and found the effect to be even greater than at Coors Field. The main reason is because Phoenix has a lower relative humidity than Denver (20 percent compared to 30 percent). In the comments to the article linked above, he predicted the use of a humidor would reduce home runs at Chase Field by 37 percent, plus or minus 6.5 percent.
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That would be a significant change. A 37 percent reduction in home runs at Chase Field in 2016 would have dropped the Arizona Diamondbacks from 16th overall in home runs to around 27th based on 2016 home run splits for the team. So don’t believe Derrick Hall when he says, “Again, I don’t know if it’s going to make a difference. It hasn’t made a huge difference at Coors Field, I don’t think.” Maybe he’s using the currently popular “alternate facts” explanation, but the truth is it did make a big difference at Coors Field and likely will make a big difference at Chase.