Thin Air and Coors Field

I read an interesting summary of an academic article titled "atmosphere, Weather, and Baseball: How Much Farther Do Baseballs Really Fly at Denver's Coors Field?" in the November 2003 "By The Numbers" newsletter published by SABR. Interestingly, the authors of the article found that average fly ball distance at Coors Field was only 3% greater in the period from 1995-1998 when you take into account the larger dimensions at Coors and the prevailing winds which typically blow in. This is not even as great an advantage as Mark McGwire enjoyed in 1998 in St. Louis.

As a result, the greater homerun rate per at bat (.044 at Coors from 1995-2002 versus .029 for other NL parks) is attributed to the impact of thin air on breaking pitches and low humidity making the ball harder and therefore more difficult to grip for pitchers.

So it seems that perhaps the focus on how the ball carries at Coors has been overblown and the effect on pitchers underestimated. This also explains why Coors seems to affect some pitchers more than others.