Yesterday, August 10th,  it was reported by Ben Lindberg of The Ringer that, “MLB quietly installed potentially exit-speed-suppressing humidors in Fenway Park, Citi Field, and T-Mobile Park prior to this season, extending a list of humidor-equipped parks that previously included Coors Field and Chase Field”.



So, what does this mean for baseball and for your fantasy players?


Here’s what we know:


* According to Alan Nathan, known Physics Professor at UIUC, after the installation of the humidor in Colorado the home runs for the Rockies dropped by 25% You can read that article here.

* In that same article Professor Nathan stated (Prior to the 2018 humidor installation in Arizona) that, “I am very comfortable saying that, with the humidor running at 50 percent and 700F, there will a reduction in home run production at Chase by 25-50 percent. While it would be nice to come up with a more precise prediction, we should not lose sight of the principal takeaway that the installation of a humidor will reduce the number of home runs substantially.”

* In 2018 the home runs at Chase Field declined by 20.47% as compared to 2017.

* Home runs in MLB from 2017 to 2018, on non-bunted balls, declined from 4.86% to 4.48% (A 7.73% drop).


Impact of the humidor


Was this drop in home run production in Arizona was largely due to the humidor? It’s not that simple. When comparing the 2018 actual stats to the 2018 expected stats home runs were actually expected to be down by 21.30%. This actual drop and the expected drop must be due to lower exit velocities? Actually, no. In 2017 the average exit velocity in Arizona was 88 MPH and the average distance was 167.7 feet. In 2018 the average exit velocity was also 88 MPH and the average distance was 166 feet. Has the humidor made an impact in Arizona? Absolutely. Has it impacted as much as we feared? It hasn’t, at least in home runs. This may be due to the humidor settings not being 50% and 70 degrees or the fact that many games are played indoors at Chase Field versus Coors Field being exclusively outdoors may be playing a role. When comparing pre-humidor Chase Field’s actual and expected stats to post-humidor Chase Field’s actual and expected stats this is what I found:


Average:               -4.08%

Singles:                 -1.08%

Doubles:               -13.14%

Triples:                 -12.38%

Home Runs:         -0.40%

Slugging:              -3.77%

wOBAcon:            -3.35%

RBIcon:                 -3.83%


Why Should You Care?


“That’s great Statcast geek, what does that have to do with Fenway Park, Citi Field, and T-Mobile Park”? Easy, easy, easy. I’m getting there. I hadn’t seen Chase Field broken down before so I presumed that you hadn’t either. There are some pretty fantasy significant players on the Diamondbacks and there are even more that make their way to Chase Field as visitors. Calm down, I’m getting there.

Believe it or not, if you have hitters on the Red Sox, Mets and Mariners this humidor might actually be good news for you, especially in Boston. Check out this info that I got from an article written on November 6, 2014 by Ryan P. Morrison of SB Nation

“To look at how the use of a humidor might affect offense in each MLB city, I’m using humidity data from the National Oceanic and Atmospheric Administration that seems to match up with what Dr. Nathan used. It’s annualized (good), using averages of all measurements (every three hours) for each calendar month; the numbers below are the average of the April through September monthly averages. The batted ball distance is only for home runs, and is based on the fact that Dr. Nathan came up with a 13.2-foot change (at Coors) for a fifteen percentage point change in humidity. I’m including Buffalo as a maybe-not-terrible replacement for Toronto, and throwing Oakland in with San Francisco.”


The below table is from the referenced article by Ryan P. Morrison at SB Nation


City Humidity (%) HR distance (feet)
Atlanta 53 2.8
Baltimore 52 1.9
Boston 59 7.9
Buffalo 56 5.6
Chicago 53 2.9
Cincinnati 53 2.6
Cleveland 57 6.2
Dallas 47 -2.6
Denver 35 -13.1
Detroit 53 2.5
Houston 56 5.0
Kansas City 53 2.3
Los Angeles 67 14.7
Miami 65 12.8
Milwaukee 60 8.9
Minneapolis 50 0.1
New York 53 2.2
Philadelphia 53 2.5
Phoenix 18 -28.5
Pittsburgh 52 1.6
San Diego 64 12.6
San Francisco 59 8.1
Seattle 53 2.9
St. Louis 52 1.3
Tampa 59 8.2
Washington DC 52 1.6


As you can see from the chart above Boston stands to gain an estimated 7.9 feet, New York 2.2 and Seattle 2.9. These positive impacts are nowhere near the negative impacts of a humidor at Coors or Chase Field’s but every little bit helps when we’re dealing with a ball that’s deader than 2015. But, that’s an article for later on in the week…