Looking back at how the “environmental chamber” at 20th and Blake changed baseball

Former Rockies right-hander Jason Jennings chuckled at the absurdity of the question.

“Yes, of course, the humidor made a difference,” he said. “It 100% made a difference. For pitchers, it was about surviving. “

It’s been 20 years since Jennings was the runaway winner for National League rookie of the year, and 20 years since the Rockies began storing baseballs inside a humidor in an attempt to bring some semblance of baseball sanity to Coors Field.

In fact, it was 20 years ago Sunday that The Denver Post broke the story.

“At last, the Colorado Rockies have discovered a way to tame baseball at altitude,” wrote former Post Rockies beat writer Mike Klis. “This is not a rehash of the dismantling of the Blake Street Bombers. Nor did the Rockies suddenly draft a cadre of 100-mph-throwing pitchers. And no, the groundskeepers did not, as manager Clint Hurdle suggested last week, find the altitude plug and stick it back in at Coors Field.

“This is about the humidor. A baseball humidor. “

Or, as Keli McGregor, the Rockies’ late team president preferred to call it, “an environmental chamber.”

The Rockies began building the chamber after the 2001 season. On March 31, eight days before their home opener against Houston, the Rockies started humidifying baseballs.

Now, 20 years later, every Major League Baseball team stores baseballs in a humidor in an attempt to provide an even playing field, regardless of the temperature and humidity at each ballpark. MLB decided to set the humidor to one setting – 70 degrees and 57% relative humidity – across all parks except for mile-high Coors Field, which uses 65% relative humidity.

“I didn’t have an issue with it before, and I can see the value of it now,” said Dr. Meredith Wills, a sports data scientist who has a Ph.D. in astrophysics. “We’ve seen how it’s worked in Colorado and Arizona with dry conditions. The humidor, in more humid areas, will end up drying out the baseballs.

“The humidor is supposed to replicate the bounciness of the ball off the bat, in every park. The point of the humidor is that the balls react the same and should all end up around the same weight. “

But now, as was the case 20 years ago, there is controversy surrounding how MLB cares for its baseballs and how that affects the game.

“Nobody knows,” Dodgers pitcher Clayton Kershaw, a three-time Cy Young Award winner, recently told The Los Angeles Times. “Whatever MLB says, they don’t know either. Way Every way they rub up the ball is different. Every ball that they make is different. Every way that they put the mud on the ball is different. Every way they check guys now. It’s all a crapshoot. Nobody knows. Whatever MLB thinks is going to happen, it’ll probably be the opposite. “


MLB’s first humidor was the brainchild of Tony Cowell, electrician and crew foreman who helped build the ballpark at 20th and Blake. He was bothered by Coors Field’s infamous reputation.

RJ Sangosti, The Denver Post

Tony Cowell came up with the idea for the humidor at Coors Field on May 5, 2022 in Denver. Cowell holds the baseball that he cut open with his bandsaw when he first thought about the idea of ​​the humidor all of those years ago.

So, after the 2001 season, when McGregor asked Rockies employees for suggestions to help make the organization better, Cowell started brainstorming. The idea for a humidor came to him during a hunting trip at 10,000 feet.

“I was elk hunting in the Flat Top Wilderness when the thought popped into my head,” recalled Cowell, 60. “I was hunting up there and I had on this old pair of leather hunting boots and they got all wet and dirty.

“Then they dried out and they got really uncomfortable. I remember thinking, ‘I hate the way these things shrink up when they dry out. That’s when I sort of put two and two together. ‘Wait a minute, my boots are made of leather. A baseball’s outsides are made of leather. It’s not just about the altitude. The baseballs are drying out, just like my boots. ‘ ”

There is no question the humidor was a game-changer at 20th and Blake.

“I really didn’t have an expectation of its effect, but I certainly was hopeful when we installed it,” said former Rockies general manager Dan O’Dowd. “The humidor didn’t necessarily help lower our team’s ERA, post-humidor, but the home runs dropped dramatically. It definitely helped normalize the game to some degree. “

But current Rockies left-hander Kyle Freeland, who was born and raised in Denver, doesn’t see the humidor as complete salvation for pitchers at Coors, especially when hot, dry weather arrives in July and August.

“Baseballs at sea-level feel still a little bit softer and a little bit easier to grip than they do here,” Freeland said. “And in my opinion, by the time the balls get out of the humidor and sit in those bags where they’re stored pregame, it doesn’t have (as much) effect.

“Because I’ll get a baseball from the umpire and it will feel slick and chalky and the mud isn’t allowed to settle into the leather. So you have to keep rubbing it, using saliva, sweat or whatever, to get a good grip on it. The ball is still different than in LA or San Diego. “

Still, 20 years of statistics show the humidor has helped Rockies pitchers, while also hurting the club’s hitters.

From 1995 to 2001, Colorado’s average team ERA was 6.14 and the pitching staff gave up an average of 126.7 home runs per season. But from 2002 to 2021, the average ERA shrank to 5.06 and home runs dropped to 98.8 per season.

The pre-humidor, the Rockies’ batting average at Coors was .328 and they hit 128.3 homers per season. Post-humidor, the average fell to .295 and home runs tumbled to 103.2 per season.

To be sure, there have been some other elements at work.

In response to the so-called “steroid era,” MLB implemented league-wide performance-enhancing drug testing in 2003.

In 2019, “juiced baseballs” resulted in 6,776 home runs hit during the regular season, which shattered the previous MLB record, set in 2017, by nearly 11%. Rockies pitchers served up 144 homers in 2019, tied for the second-most in Coors Field history with the 2001 staff. Colorado’s 1999 pitching corps gave up 159 homers.

In that first year of the humidor, runs were down 11 percent at Coors Field across the board from 2001. Even more telling, the Rockies posted their lowest ERA (5.47) and batting average (.312), easily eclipsing the marks of 5.67 in 1997 and .316 in ’95.

Former Rockies’ first baseman Todd Helton gave a thumbs-up to the humidor, telling The Post at the time, “I like the way the games have been going. It’s a lot more fun for the fans, for us. It’s actually easier to hit that way when the games don’t take as long. You are not standing on the field forever. If our pitchers like it, I like it. That’s all that matters to me. “


Jennings did OK in his first start at Coors in September 2001, but his next outing was a disaster. He stuck around for just 1 1/3 innings, giving up seven runs on seven hits, with two walks against the Padres.

For Jennings, and other Rockies pitchers of the pre-humidor era, the biggest problem wasn’t that baseballs carried farther at altitude. Their complaint was that they couldn’t get a proper grip on the ball.

“The problem was, the baseballs would shrink,” Jennings recalled. “The balls would dry up and you couldn’t feel the seams. It was insane. I mean, it was like, ‘You expect us to pitch against the Barry Bonds of the world, a mile above sea level, with a cue ball?’ Which is basically what we were throwing.

“The (clubhouse attendants) would rub the balls up with the mud they used and that did us no good. All it did in Colorado was turn the mud into a dry powder, essentially. Then we’d have to wipe that away. “

Jennings said he could grip the ball better beginning in 2002 when he finished with a 16-8 record and a 4.52 ERA.

On June 20, 2006, Jennings and relievers Tom Martin and Brian Fuentes combined for a one-hit, 6-0 shutout of Oakland at Coors Field. Athletics manager Ken Macha, on the wrong side of the first one-hitter in Denver, sniffed a conspiracy.

“I still feel the (humidor) should be investigated,” Macha said. “Maybe we ought to do that at our ballpark. The ball’s the same weight, but they are sitting in there and getting moisture, so I don’t understand that. It’s like getting your golf ball out of the water – find one out of the water – and you hit that. “

In 2010, Giants Cy Young Award winner Tim Lincecum essentially accused the Rockies of cheating, hinting that they used non-humidor baseballs when they came to the plate.

((Expletive) juiced ball. This is (expletive), ”Lincecum was caught on camera saying.

After Giants general manager Brian Sabean complained, MLB ordered changes in how baseballs were monitored at Coors. Under the new procedure, umpires began carrying bags of balls out of the humidor and placing them in Colorado’s dugout where they remained in the umpires’ view.

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