[Gambo]

I'm not mad about the criticism as it may be justified but there are a few things that need to be straightened out.

1) First, I didn't create the park factors, I just implemented them into my database with some minor tweaks. I originally was skeptical of them and then when I started crunching the numbers was pleased with what I saw.

2) Park Factors - a statistical analysis of stats produced in a ballpark compared to the league average of that season.
Gambo Park Ratings - a statistical analysis of what stats should be produced by a parks dimensions and location based purely on the average of all historical major league parks. (1.0 generated as the average of all current parks)

"Park Factors" are not the end all and be all of rating a ballpark. The problem with park factors is two fold. 1st, it is based on the players who played there's stats and not the field at all. People assume that over a long period this corrects itself but 1/2 of the stats used are still based on the same set of players. 2nd, park factors are rated on each season. My park ratings are based on modern ballparks being 1.0. Older parks were generally larger with odd dimensions so compared to modern parks you would expect higher numbers.
Take your Polo Grounds example. During it's existence ballparks like Braves Field, Old Yankee Stadium, Navin Stadium existed with HUGE playing areas. Overall, compared to those parks (it's short corners and deep center combined with the playing style ) resulted in less hitting compared to the average park. Park Factors reflect this. Now put the Polo Grounds in a modern environment. Those deep gaps and short porches would result in modern hitters and speedsters having a field day. If you want to see the truth load up any "arcade" game with the Polo Grounds in it and play a few games with modern players.

3) I'll reiterate. The ratings are based purely on dimensions. I would not be naive enough to say the ratings are the best they could be BUT, you need to understand the difference between official "park ratings" and ballpark ratings in my DB. What would be better to do to analyze my numbers is just take the parks in existence those years, adjust my ratings to 1.0 for their average and see where the Polo Grounds lay in that comparison. It will be much closer than you think.

4) As for the Fenway example. In reality Fenway allowed for certain left handed hitters to have crazy averages. Wade Boggs made a career of tailoring his swing to bounce the ball of the monster, it was his game plan and he admitted to it. Many other lefty hitters who could did this did also. Fenway is a freak.

5) If your going to do a historical replay with players on their actual teams then I would recommend using park factors and neutralized statistics if your going to a fantasy league and use a ballpark (or a bunch from different eras) use my ratings. You'll get what your looking for.