MLB.com: Early numbers show impact by Chase Field humidor

Twelve of the Arizona Diamondbacks’ 27 games played to begin 2018 have come at Chase Field, where the launch of the facility’s humidor was expected to give pitchers a better grip of the baseballs they pitched while potentially limiting the offensive output at the ballpark.

According to a study by Illinois professor emeritus Alan Nathan from a year ago, humidor-influenced balls were expected to decrease the home run rate by 25 to 50 percent due to the added weight to the balls and the (assumed) more accurate pitching. Nathan also said the average exit velocities would drop about 2 mph.

So far, those estimations seem correct.

MLB.com’s Mike Petriello dug into the numbers at Chase Field through the month of April, and the statistics and tracking data from the home start to 2018 compared to that over the last two seasons support Nathan’s theories.

Below are a few cumulative stats for the D-backs and their opponents’ offensive production at Chase Field comparing the last two seasons to this one.

• Exit velocity has dropped by 2.7 mph, from 89.6 in 2016-17 to 87.6 this year

• Home runs per game has been clipped from 2.6 per game to 1.9 per game (29.6 percent)

• Runs per game are down from 12.4 to 7.2

• Chase Field leads MLB in biggest reduction of hard-hit percentage (6.1), exit velocity drop on fly balls and line drives (3 mph) and change in weighted on-base percentage (-.075). No other venue has a hard-hit percentage that has dropped more than 2.7 percent (Detroit) and none has seen an exit velocity change on such hits fall more than 1.1 mph (Philadelphia and Cincinnati).

All of that data doesn’t account for opponent talents, but it does suggest that the trends at Chase Field aren’t lining up with those across MLB.

It does, however, indicate that either pitchers are pitching better for the Diamondbacks and their opponents, or that the balls hit are just not driving as far or being hit as hard. Likely, it’s both.

Considering the strong start by the Arizona pitching staff, the more grippable, softer balls appear to be working out well for the D-backs, whether or not it’s hurting their own hitting.

The Arizona pitching staff leads the majors with a 2.35 ERA at home (St. Louis is second at 2.79 ), 0.97 WHIP (Houston is second at 1.01) and .576 opponent OPS (Yankees are second at .619).

“There should be consistency throughout all of baseball with the feel, with the grip, with the humidity that’s involved. It’s only going to help our pitchers,” Arizona president and CEO Derrick Hall said in February. “I don’t know that it’s going to have a dramatic effect on our hitters — it’ll have some effect, it should. But overall, our pitchers are going to be so much happier. It’s not going to feel like a cue-ball. They need to grip that thing.”

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