November 9, 2004

Time to Get PADE Again

Park Effects on Team Defense

by James Click

Now that baseball’s coaches and managers have weighed in on their favorite defensive players, and Clay Davenport has unveiled his champion glovemen of 2004, I though I’d bring back an old friend for a fresh look at this year’s defensive performances.

Last year, I introduced some changes to Bill James’ Defensive Efficiency, a metric that measures the percentage of balls in play that the defense converts into outs. While it eventually ended in a measure intended to be free of both park and pitching factors called Team Adjusted Defense (TAD), I’m uncomfortable with the process of removing pitching from the operation, so for now I’ll stick to the original update: Park Adjusted Defensive Efficiency (PADE).

There will be one major improvement over last year’s version. In 2004, PADE will include instances in which a player reached on an error against the defense. For long and drawn-out reasons from which I will spare you, PADE missed that last season, but now it has been added and the metric is more accurate for it.

The first thing PADE does is generate defensive park factors for each ballpark. These will be slightly different from full park factors since defensive park factors do not include home runs. Instead, by comparing how each team plays defense at home and how they play it on the road, we can gain an estimate of how difficult each park is in which to play defense. These will be three-year factors to eliminate some of the variance for year to year with the obvious exception of the parks that have been open less than three years in Philadelphia, San Diego, and Cincinnati.

Here are the 2004 defensive park factors. The lower the factor, the more difficult it is to play defense:

Ballpark                  Park Factor

SBC Park                      .9780
Coors Field                   .9796
Sky Dome                      .9857
Fenway Park                   .9861
The Ballpark at Arlington     .9882
PNC Park                      .9898
Shea Stadium                  .9908
Metrodome                     .9954
Edison Field                  .9957
Jacobs Field                  .9961
Kauffman Stadium              .9980
PETCO Park                   1.0025
BankOne Ballpark             1.0038
US Cellular Field            1.0060
Wrigley Field                1.0139
Citizens Bank Park           1.0150
Turner Field                 1.0152
Yankee Stadium               1.0152
Comerica Park                1.0157
Minute Maid Park             1.0162
Olympic Stadium              1.0164
SafeCo Field                 1.0208
Busch Stadium                1.0233
Tropicana Field              1.0238
Dodger Stadium               1.0250
Camden Yards                 1.0251
ProPlayer Stadium            1.0255
Miller Park                  1.0262
Network Associates Coliseum  1.0312
Great American Ballpark      1.0371

There is quite a bit of interesting movement on this list with another year of data and the adding of reaching on errors. For example, SBC Park actually comes out as a more difficult venue in which to play defense than the vast expanses of Coors Field. I would assume that most of this is due to the staggering size of the outfield in SBC Park, the high wall in right, the small foul area, and the age of the Giants' outfield. Perhaps the San Francisco outfielders have a more difficult time than younger players compensating for the extra area in the outfield by the Bay. None of these reasons are actual explanations, but they seem the most plausible at first glance.

Also interesting is PETCO Park’s very average park factor despite the vast protests from many San Diego players about the park's ability to suppress offense. It’s just one year of data, but it appears at this point that PETCO’s main offensive suppression comes from turning home runs into very long flyball outs, making things easier on the defense, but much harder on Padres hitters’ agents.

The rest of this article is restricted to Baseball Prospectus Subscribers. Not a subscriber? Click here for more information on Baseball Prospectus subscriptions or use the buttons to the right to subscribe and get access to the best baseball content on the web.

Cancel anytime. That's a 33% savings over the monthly price! That's a 33% savings over the monthly price! Already a subscriber? Click here and use the blue login bar to log in.