Identifying the Best Home Run Parks in Baseball History

• Activity Number: 135
• Type: Invited
• Date/Time: Monday, August 12, 2002 : 2:00 PM to 3:50 PM
• Sponsor: Section on Statistics in Sports*
• Author(s): Michael Schell*+
• Affiliation(s): University of North Carolina
• Keywords: baseball ; changepoints

Abstract

Baseball parks are not of uniform size, and meteorological effects, altitude, visibility, and other factors make some ballparks easier to hit home runs in. Since players typically play half their games at their home park and the other half at their opponents parks, having a favorable home park can improve home run production. By identifying the park effect, players' home run totals can be adjusted, putting players on a level playing field. A new multiple changepoint method is used to identify the park effects. This method is used to identify when the park effect shifts and to estimate its size in each time period--between changepoints--when it is modeled as constant. Park effects are estimated separately for left- and right-handed hitters. Favorable ballparks like Denver's Coors Field will be revealed and contrasted with unfavorable parks, such as the Astrodome. Adjustment using the park effects reveals that Eddie Mathews and Willie Stargell each would have hit about 50 more career home runs than they did had they played in "average" parks. On the other hand, over 100 of Mel Ott's 511 home runs were the lucky by-product of playing in the home run-friendly Polo Grounds.