The file contains:
- Distance to Fence
- Height of Wall
- Surface Type, Temperature, Wind Speed, Foul Ground, and Rain Frequency
Only the park factors truly matter. The other categories are only used for a more colorful play by play. For instance, 1953 Fenway Park has Strong winds and a home run factors of 142 and 150. The wind has already been taken into account in the 142 and 150.
Similarly, and this is the tricky part, fence distance is irrelevant as well. 1904 South End Grounds had very small fences (6ft) and extremly short distances: 250ft down the left field line and 258 ft down the right field line. Yet, the park factor for home runs were 86 and 86. Four our purposes, only look at the 86.
Finally, you'll see me refer to factors from time to time in the following format:
100/102, 107/115, 105/105, 105/86.
This happens to be the park factor line for 1957 Busch Stadium. The first set of numbers (100/102) are the factors for singles, the second set (107/115) is for doubles, followed by triples (105/105), and home runs (105/86).
The first number before a slash is the factor for lefties, and the second for righties. Looking at home runs only - 105/86 - this means lefties hit 5% more home runs than average, and righties hit 14% less home runs than average. The average corresponds to the real life stats from 1957 Busch Stadium vs the rest of the National League.
In terms of ATB, Busch Stadium is 'ported' to our universe, and ATB lefty batters will hit 5% more home runs than average and lefty batters 14% fewer than average. The average in this case is not the NL in 1957, but rather the average 'era' we play ATB in.
It's the same 'era' as ATB 16 where on average batters hit .253 / .315 / .378 and pitchers recorded a 3.65 ERA and 1.28 WHIP. Last year ATB did not have a DH so expect those lines in the NL only.
Hope this helps!