Seamheads Ballparks Database adds 2012 season updates

Our friends at are proud to announce another update of the Ballparks Database, created by SABR members Kevin Johnson and Dan Hirsch.

The database includes the following updates through the 2012 season:

  • Descriptive data that includes location, date of first and last game (if applicable), number of seasons and games played, seating capacity, field dimensions, wall heights, playing surfaces, area of fair and foul ground, distance from the plate to the backstop, latitude, longitude, altitude, comments about structural or rules changes and current and historic aerial views.
  • Runs ballpark factors for every year since 1871.
  • Home run splits for every year since 1876.
  • Full ballpark factors and splits for home runs, hits, singles, doubles, triples, walks and strikeouts for every year since 1919.
  • Partial ballpark factors for years prior to 1919.

Thanks to Dan, the database section of the site is very easy to use and includes the following:

  • Sort by Ballparks, Years, Teams or Cities.
  • Filter by Active, Inactive or Both.
  • Filter by Modern Era, 1800s or Both.
  • Filter by State.
  • Averages of seating capacity, field dimensions, wall heights, area of fair ground and backstop distances for each season dating back to 1871.
  • Number of teams and venues for each season dating back to 1871.
  • Percentages of grass vs. artificial turf and open air vs. domed vs. retractable roof for each season dating back to 1965 (all stadiums were open air with grass prior to 1965).
  • One-year and three-year park factors for each individual season and/or individual ballpark, filtered by league where applicable.
  • Sortable headers in ascending or descending order .

Seamheads founder Mike Lynch adds:

As a reminder, we provide two sets of calculations: 1-year factors and 3-year factors.

The 1-year factors are observed factors, based on only the season in question. While they do use an other parks corrector as described in the detail documentation, these are essentially the factors that were observed for that particular year, so a 120 doubles factor for LH batters in Fenway Park means that left-handed batters hit 20% more doubles at Fenway than LH batters for those same teams’ batters hit in games away from Fenway.

The 3-year factors are attempts at calculating “truer” factors.  There are many, many ways we could have constructed our formula, and it’s difficult to determine what the “best” way is, but we believe our way is at least a good and defensible way.  Our basic formula is to use the 1-year factors for the season in question, the season immediately preceding, the season immediately following, and then the park’s long-term historical factor, all weighted equally.  As some parks have rather long histories, while other may have life for only a few seasons, this is not a perfect method, but we believe it retains a basic simplicity while providing for a high degree of accuracy in estimating a park’s impact on offensive events.

We welcome any feedback on any of the data or suggestions for improvement, so try it out and enjoy!

To view the Seamheads Ballparks Database, visit


Originally published: March 20, 2013. Last Updated: March 20, 2013.