This is an explanation of how I re-worked the wild-pitch/passed-ball system.
The fundamental problem with the PtP WP/PB system was that it based the pitcher ratings purely on WP and the catcher ratings purely on PB. Furthermore, there was no adjustment made for the pitcher/catcher combination. From a game mechanics standpoint there is no fundamental difference between a WP and PB, it is really just a scoring decision. Therefore I decided to treat WP and PB as the same event and design a system which would attempt to get a more accurate distribution of the combined event.
The first step is to calculate the overall WP+PB rate for each MLB team. The next step is to calculate an adjusted average rate for the entire league, “adjusted” meaning that we account for the fact that the WP/PB range on the pitcher card is actually too small to account for the full range of variance. There are pitchers who throw WP so often that even if all WP/PB events were WP it would not be enough (these are the guys who get WILD-WP!), so the “adjusted” average just means it accounts for the fact that not all WP come from the WP/PB chart.
Once we have the team rates and the adjusted average, the next step is to assign responsibility for 50% of the variance from average to the catchers and 50% to pitchers, and then assign each team’s pool of catchers and pitchers a separate overall rating. After that is done individual ratings for pitchers and catchers are assigned by referencing their WP+PB rate against the overall rating for the team’s opposite end of the battery.