I've collected a "considerable" amount of data to try and determine some rudimentary park factors for Hardball from the limited amount of data that WIS gives us.
Because WIS doesn't give us runs scored when we look at stats for home and away, these won't be exact to what you might find other park factor systems are based on. The stats that we are given for batting home/away and pitching home/away that we can do some simple work with are H, HR, AVG, OBP, SLG, and OPS(if we add OBP and SLG for pitching).
While not exactly a perfect measure of offensive output, I based these park factors on OPS, but can provide ratings for the other categories listed.
To get to the final number, this is the formula I used: (home batting OPS + home pitching ops)/(away batting OPS + away pitching OPS). I didn't do any of the different adjustments that other systems may use, because the data from WIS is lacking.
I grabbed every completed season from 12 worlds, encompassing more than 821 seasons: American Pastime, Big Sky Alumni, Cooperstown, Fingers, Mantle, Major Leagues, Moonlight Graham, Public Works, Second City, Summer of '49, Vin Scully, and Warning Track to come up with these. Some cities are lacking data, mainly Omaha, Tucson, Montgomery, and Cheyenne just to name a few.
The second column is the number of seasons of data I've collected for each city. The third column is the average park factor for OPS for the seasons I've gathered; 1.000 is exactly average. The last column is the margin of error based on a 95 percent confidence level. For cities with more than 70 seasons worth of data, it typically holds to within .006 +/- the average, so we can be fairly certain it's pretty close. To get a MOE of less than .004 would take more than 300 seasons worth of data for each city, depending on its standard deviation.