Glad You Asked That

Ever wonder why there seem to be more home runs at Coors Field in Denver, Colorado, than at other major ball parks? The answer might be due to the air up there. Denver is known as the “Mile-High City.” Its high altitude decreases the amount of air resistance on batted balls so the balls travel farther when hit. Plus, the low air pressure means the pitches “break” less severely and are therefore easier to hit. To combat this, the baseballs used in Coors Field games are actually placed in a humidor beforehand to increase their weight.

Earlier this year, Jay Schaffer and Erik L. Heiny, both mathematicians at the University of Northern Colorado, analyzed the effects of elevation on slugging percentages in major league baseball in 2003. They found that the slugging percentage in Coors Field is significantly different from that in any other ball park. In fact, it's about 9.2 percentage points higher than at middle elevations (defined as between 500 and 1100 feet), and about 12.5 percentage points higher than at elevations below 500 feet.

A few years ago, US Naval Academy scientist Howard Penn determined that because of the elevation, a baseball travels roughly 10% farther at Coors Field than it does in other stadiums. Furthermore, when Penn compared the number of home runs hit by teams playing at home versus that same team on the road, the Rockies really stood out: in 2001, 58% of their home runs occurred at Coors Field. And a full 60% of the home runs at Coors Field were made by batters from visiting teams. Over the last decade, four of the

Rockies' star players have pooled their efforts to snag six national league batting titles.

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