Baseball Judgments

Baseball Judgments |
Renewed ballpark factors


By Roger Weber


(through 2005)


Click here to download park listing


These are renewed ballpark factors. The numbers work like ballpark factors. Unlike normal ballpark factors, they exclude biases due to good or bad teams or an especially good or bad league. Normal ballpark factors have a flaw – they assume ballparks change between years. Aside from weather and chance, they don't. These eliminate that assumption.


These are averages of all parks since 1900 against their eras. Ordinarily I'd try to list ranges instead of specific numbers, but in this case the actual numbers are necessary. The ones with asterisks are stadia that were open fewer than eight years and thus don't give a perfectly accurate measure. Remember these are based on runs, not home runs or hits. So some homer parks might show up low but it's because not that many runs are scored there. The numbers are also most accurate for parks that existed for not a terribly long time. The years chosen for measure were taken through a random stratified selection.


Essentially, the formula is pretty simple (Ballpark A = the park listed):

  • (Team A 's runs scored at Ballpark A + opponent's runs at Ballpark A) / (Team A's runs scored at all other ballparks + opponent's runs scored in games against team A in ballparks that are not ballpark A)

Click here to download park listing



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