I took players that were playing in neutral fields, from the same positions, then compared their RC to their PB value. This gave me a constant that had very little variance over all the players. When this (constant * RC) was applied to players in better hitting parks, their PB was slightly lower than this number, while the opposite was true for pitching parks. From this I was able to see that positions like SS and C were being adjusted upwards, and OF's were being adjusted downwards.