In 2005 I implemented a regression algorithm for the LH/RH splits on the cards, replacing the legacy PtP method of basing each side of the card on the raw split data. This is a brief explanation of the rationale and methodology.
The only way the legacy PtP system can generate accurate results is if the “user” ensures that each card receives the proper PA distribution of LH/RH. What years of experience have shown is that our “users” do not do this, nor do they want to do this. The game isn’t as fun when player usage is rigidly enforced. Therefore, the PA distributions are not allocated properly and the overall player performance is skewed. If we strike a balance between replicating the platoon split and replicating the overall performance of the player we will improve the overall accuracy of the system.
Now, one one end of the spectrum we have games which ignore platoon splits or enforce a standard split for all players, and on the other end we have the PtP-inspired system which treats vLH/vRH data separately. I decided that a hybrid system, one which regresses platoon splits toward the norm, retains the original intent of the PtP system which we all enjoy while making the game more accurate in reproducing overall performance. This rationale is not based on ability, but rather on a tacit acknowledgement of how our “users” interact with the product.
Once the raw target totals have been calculated for a player card, they are passed into the regression algorithm. The regression algorithm takes the existing LH/RH ratio, and regresses it on a sliding scale toward the standard ratio (LL/LR for LH, RL/RR for RH).
Regression amount is a simple linear function starting at 75% for 0 PA and scaling down to 0% at 900 PA. This divides neatly, with 300 PA being the 50% point and 600 PA being the 25% point. For each event, we determine which side generated more offense and use that PA sample as the value to plug into the regression function. We do this because the offense has final decision on the pitcher/batter machup.
When adjusting the events to match the new target ratio you have to use an “exchange rate” based on the PA split. So, if you’re moving events from the LH side to the RH side you have to do so at the ratio of RH/LH PA.