It was six years ago that Tony Cowell, an employee in the Colorado Rockies' engineering department, noticed his leather boots would dry up and shrink over the summer. He wondered whether cowhide baseballs were doing the same thing in Denver's mile-high, thin and dry desert air.
The ballpark had a reputation at the time for all the home runs that were launched over the walls - and many pitchers kept complaining it felt as though they were throwing billiard balls, because the baseballs were drying out, becoming smooth and slick.
After many tests, it turned out Cowell was right. The Mile High City was drying out the balls, making them smaller and able to travel further - resulting in more home runs.
The Rawlings balls were officially smaller than Major League Baseball's standards. They require game balls to be between 142 and 149 grams with a circumference of 23 to 23.5 inches. The Rockies sold MLB on the idea of a climate-controlled vault to store the baseballs in their boxes on metal racks.
So the Coors Field humidor was born. It's a small greenhouse-like room that is best compared to a smaller version of the keg coolers you see at the ballpark at beer concession stands.
Baseball hasn't been the same since in Denver. In 2001, there were 268 major league homers hit out of Coors Field. This year, there were only 185.
Aside from keeping their original form, the humidor baseballs also have a better grip, so pitchers have full command of their cowhide.
The humidor holds about 400 dozen baseballs and a new shipment of 142 came in just this week, those are the World Series balls.