Why Were Baseballs Sailing out of Coors Field Last Year?

On June 16, 2019, the Rockies clubhouse was hushed, as if someone had pushed mute on the typical post-game commotion. The team had just lost that day’s game to the San Diego Padres, 14-13. Losses aren’t unusual in a 162-game season. What was unusual was this: Over the previous few days, the two teams had combined to score 92 runs, the most ever for a four-game series in history. The players were processing the loss, yes, but it was the hit parade that had engendered the bewilderment. “I don’t really know what to point to,” said outfielder Charlie Blackmon during a post-game presser. “The hitting was good. I’ve seen pitching be better. It was hot. It was dry.” Everything he mentioned probably played a role, but the Rockies would come to understand there was another factor at play: the baseball.

When Coors Field opened in 1995, everyone knew it would be the most hitter-friendly ballpark in MLB history. On average, a baseball travels five to nine percent farther at 5,280 feet than at sea level. The thin air also gives off-speed pitches like curveballs less break, making it more difficult to keep batters off balance. To limit the effects of elevation, the Rockies built a humidor in 2002 so they could store game baseballs at 50 percent humidity, preventing them from drying out and thus carrying farther. It worked. Before that year, Coors surrendered an average of 3.2 home runs a game. That dropped to 2.39 from 2002 to 2010.

Just weeks into last season, home runs were up across baseball, and many folks speculated the increase had to do with so-called “juiced” baseballs. Rob Manfred, MLB’s commissioner, did say the balls Rawlings manufactured for 2019 might be more aerodynamic, but most teams, including the Rockies, weren’t willing to publicly impugn them just yet. “It took them awhile to suss it out,” says Nick Groke, who covers the Rockies for the Athletic. “In the moment, I don’t think anyone really knew exactly what was happening.” One thing was clear, though: Baseballs were flying around Coors Field as if gravity didn’t exist. During a 15-game stretch from June 12 to July 15, the Rockies gave up 9.9 runs per game while scoring 7.6 runs per game. Those numbers, which were partly the product of poor pitching on both sides, were unlike anything the park had seen since the late 1990s.

A few months after the season ended, Rockies manager Bud Black was more certain about the baseball’s role. “Something was up with the ball,” he says. “I don’t think it was anything that was planned by anybody. I just know from being a part of this game for 40 years that it was just a little different to even touch and feel.” Black’s anecdotal evidence has been backed up by science. MLB commissioned an independent study to look into the sport’s home-run surge. The findings, which were released this winter, determined the increase was 60 percent due to changes to the baseball—most notably, a lower seam height that created less drag—and 40 percent due to hitters actively trying to hit more long balls.

Black is quick to point out that both teams have to play with the same balls. While that’s true, only one squad has 81 home games in a setting where the stitched spheres are already meeting with less air resistance. At the league’s winter meetings, MLB did indicate it would try to provide insight about any changes to the balls for 2020. However, it also said there won’t be enough time to fully test the balls between manufacturing and opening day. That meant the Rockies were still left guessing as they headed to spring training.