Park Factors are a flawed mechanism when used to compare individual players from different teams. PF is a measurement of totals runs at home compared to total runs away. Yet this number is then used to augment individual players batting lines. Stats like OPS, AVG, Home Runs, Runs and RBI's. As well as the doubles, triples, hits, and walks. Of course the trouble with doing this is that it assumes that all these different events are affected by the park the same as total runs and that individual players all basically accumulate stats the same way. In otherwords if a park increases scoring by 10% then it also increases home runs by 10 percent, as well as hits, doubles, so on and so on. And that individual players will hit 10% more home runs at home then on the road.

By looking at the components we see that it isn't even close to the truth. Looking below at the chart the first stat listed is the traditional Park Factor. The one that is gathered by comparing runs at home against runs away. The next is for home runs done the same way, then hits, doubles, triples, and walks.

Take the Red Sox as an example, last year they had a PF of 106. Most people would then use that number to adjust a players OPS and home runs totals. Saying something like Player A batted .320 with a OPS of .950 with 40 home runs, but once we adjust it he is now batting .302 with an OPS of .896 and 38 home runs. But by looking at the components we see that the players HR totals should not have been adjusted (99 HR factor), that his hits were not increase by 106 but by 105 and that his walk total was increased by 106 but decreased by 99. Last year before park factoring this player would have an OPS roughly 24% better then the league, after PF it would be 17% better then the league. But looking at his components we would see that his OPS would be at least 20% of the league if we were to adjust each individual stat based on the park factors for each individual stat.

Of course all this ignores the other obvious flaws in PF which are that it ignores what side of the plate you bat on and whether or not the individual batter actually played the same ratio of home and away games that his team did and that he played every game. For example if you have a player who played 130 games and missed 3 games at Coors Field, 3 games at Arlington, and 6 games at the Cell his park factor adjusted numbers are going to be radically different the his teammates who did play those games.

By looking at the components we see that it isn't even close to the truth. Looking below at the chart the first stat listed is the traditional Park Factor. The one that is gathered by comparing runs at home against runs away. The next is for home runs done the same way, then hits, doubles, triples, and walks.

Code:

Park Name ParkFac HRFact HitFac 2BFac 3BFac BBFac Rockies 121% 112% 112% 116% 133% 109% Rangers 111% 104% 105% 104% 133% 100% White Sox 107% 120% 105% 99% 94% 101% Blue Jays 106% 106% 103% 104% 110% 105% Cubs 106% 116% 102% 100% 96% 99% Red Sox 106% 99% 105% 117% 80% 99% Orioles 104% 103% 101% 102% 85% 98% Giants 103% 95% 104% 105% 141% 97% DBacks 103% 115% 103% 106% 115% 101% Twins 102% 96% 101% 98% 87% 97% Brewers 102% 99% 99% 108% 112% 106% Phillies 101% 107% 99% 93% 118% 100% Athletics 101% 104% 99% 99% 84% 103% Astros 100% 104% 100% 95% 122% 96% Braves 100% 106% 99% 97% 87% 101% Mets 99% 90% 102% 99% 73% 99% Angels 99% 103% 101% 93% 79% 98% Indians 98% 87% 98% 106% 89% 106% Cardinals 97% 90% 100% 102% 113% 103% Tigers 96% 94% 100% 91% 142% 99% Yankees 96% 101% 98% 94% 77% 97% Pirates 96% 94% 99% 104% 90% 95% DRays 96% 100% 97% 95% 102% 101% Royals 96% 85% 99% 97% 121% 99% Dodgers 95% 101% 98% 88% 80% 92% Expos 95% 93% 97% 107% 94% 100% Marlins 95% 99% 98% 97% 101% 103% Reds 92% 102% 95% 93% 77% 94% Padres 92% 85% 95% 95% 126% 102% Mariners 92% 102% 93% 102% 74% 102%

Take the Red Sox as an example, last year they had a PF of 106. Most people would then use that number to adjust a players OPS and home runs totals. Saying something like Player A batted .320 with a OPS of .950 with 40 home runs, but once we adjust it he is now batting .302 with an OPS of .896 and 38 home runs. But by looking at the components we see that the players HR totals should not have been adjusted (99 HR factor), that his hits were not increase by 106 but by 105 and that his walk total was increased by 106 but decreased by 99. Last year before park factoring this player would have an OPS roughly 24% better then the league, after PF it would be 17% better then the league. But looking at his components we would see that his OPS would be at least 20% of the league if we were to adjust each individual stat based on the park factors for each individual stat.

Of course all this ignores the other obvious flaws in PF which are that it ignores what side of the plate you bat on and whether or not the individual batter actually played the same ratio of home and away games that his team did and that he played every game. For example if you have a player who played 130 games and missed 3 games at Coors Field, 3 games at Arlington, and 6 games at the Cell his park factor adjusted numbers are going to be radically different the his teammates who did play those games.

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