Why baseballs are stored differently at Coors

December 4th, 2020

DENVER -- Long before the Rockies entered the Major Leagues, and the Rocky Mountain air changed the game, renowned baseball essayist Roger Angell wrote this about the object essential to the sport:

“Any baseball is beautiful. No other package comes as close to the ideal in design and utility. It is a perfect object for a man’s hand. Pick it up and it instantly suggests its purpose: It is meant to be thrown a considerable distance -- thrown hard and with precision.”

Beautiful words, until they started playing baseball in Denver in 1993. The men pitching this perfect object would hear it crash against a bat, then whip their heads in horror as it sailed far.

Needing not only to restore the game’s poetic balance, but to save pitchers from insanity, the Rockies had to install the so-called humidor -- a temperature- and moisture-controlled chamber for storing baseballs at Coors Field. Since 2002, the balls have been kept at 70 degrees and 50% humidity, in a 9-by-9-foot, 7-foot high chamber that looks like a walk-in cooler.

While baseball at altitude remains different and usually higher-scoring -- especially when the Rockies are strong offensively -- the humidor has made the game fairer for pitchers.

But why?

It is well-known that the ball would travel in the mile-high atmosphere, where air pressure is roughly 15% lower than at ballparks at sea level. That means some fly balls become home runs.

To combat this, the Rockies designed a big park, with more outfield area than any in baseball. However, the dimensions didn’t reduce scoring because outfielders discovered there was no good place to position. Stand deep, and either soft fly balls landed, or runners could take an extra base by the time the fielder could reach it. Play shallow and watch fly balls that didn’t go for home runs land in the expansive outfield, or carom crazily off the wall.

So, not much could be done about the batted ball. But that was just one problem.

The other issue was thrown balls didn’t break or sink the way they did at sea level. Less break, whether vertical or horizontal, meant a sweeter pitch for a hitter. Was there a way to combat that? Nothing could be done about the air pressure, but could that really be a factor in the 60 feet, 6 inches between the mound and home plate?

The answer was in the hunting boots of Tony Cowell of the Rockies’ engineering department.

Tony Cowell, an engineer at Coors Field, inspects a dozen baseballs stored in a walk-in humidor at Coors Field in 2002.AP

After the 2001 season, Cowell noticed that his boots had dried and shrunk since the previous winter. People dedicated to their craft are always thinking. Sometimes, a hobby clears the mind and allows new ideas to enter.

Cowell had one: What if Denver’s atmosphere did the same to baseballs that it did to his boots?

Some of the tests were as simple as dropping baseballs on concrete and noticing that the drier ones bounced higher. Others were, well, stuff an engineer knows to do.

In addition to reducing bounce, thus reducing the force off the bat, protecting the cowhide also meant they were less slick. That meant better grip for pitchers. A sure and consistent grip is key to the pitcher exerting control, especially on a breaking ball.

No longer were the boxes of baseballs simply stacked in the hallways upon arrival.

Jay Alves, former Colorado Rockies vice president of marketing, is seen with some baseballs in the club's humidor before the start of Game 3 of the 2007 National League Championship Series.AP

Basically, the humidor is keeping the ball at the manufacturer’s specifications in terms of size. And with the chamber combating the drying effect, it’s a little easier to grip.

While the humidor is effective, it isn’t magical. Pitchers still experience less consistent break and movement than on the road. Conversely, hitters see a less-effective pitch at Coors than on the road -- a factor that vexes offensive players, who struggle with going in and out of Denver’s atmosphere through a season. With no other team playing at anywhere close to the same altitude, it’s a unique challenge.

But this much is known: Dried-out hunting boots led to the first steps in MLB’s ball-storing revolution. A humidor was installed at Chase Field ahead of the 2018 season, the same year that MLB standardized how all 30 clubs are to store baseballs.

Now, it’s not just that the ball fits in the pitcher’s hand.

It’s that the pitcher trusts it a little more when it leaves his hand.