Park factors are among the most overrated "stats" among statheads. Non-statheads don't even think about them. The use of statistical formulas in this regard is to normalize the data so that someone can make a judgment between two or more players that play in different environments. However, the SD for park factors is so small that most of the time the data have very little meaning. Outside of places like old Coors (before the humidor) and Petco/Comerica most places play relatively similar. The question that's important is, does player A perform better in park 1 than he would in park 2? A guy like Slappy was able to take advantage of Coors and Pro-Player because they had huge outfields. He really is/was a better player when he played in Coors b/c the park suited his abilities. A guy who drives the ball in the gaps isn't going to be as good in Pro-Player as he would in a more symmetrical park. A guy like Hamilton who mashes the snot out of the ball will still mash the snot out of the ball anywhere he plays. So that means he's very likely to play well in a hitter friendly environment and play well in a pitcher friendly environment. All and all I would just look at OPS+ to try to determine offensive output when comparing players. Thanks, but I get all that. My question is how (or why) does a place like Rangers Ballpark go from 5th to 19th to 1st in park factor in a 3-year span. If you don't change the structure (or something like a humidor) how can the same park be hitter friendly, pitcher friendly, than the most hitter friendly place in 3 consecutive years. B/c they use runs scored as the primary dependent variable.