THE BOOK--Playing The Percentages In Baseball

Tuesday, November 21, 2006

Forecasting Playing Time

Ever wanted to figure out how many more plate appearances a batter will get to the end of his career?  There are several parameters to consider, with current playing time and age as two key pieces.  Other important information would be the quality of the batter, past playing time, fielding talent, positon, and expansion among others.  What I’m going to show you is how to do a basic forecast using two paremeters (age, and PA in most recent season):

Future PA = [PA]*((67/[age])^2) + (67/[age])^6.7 - 650

For example, a 30-yr old, with 575 PA in that season will forecast for 2436 additional PA to the end of his career.  In reality, all 30 year olds (74 of them) born between 1930 and 1960 who had between 550 and 600 PA actually averaged 2384 PA. 

I will post the actual data on my site soon, and I encourage others to come up with something nicer than mine, a better fit, and does away with possible negative PA.