One of the cool things (ok, I’m a baseball nerd) about analyzing data is how often you discover little interesting facts that you didn’t know before.
While researching my current work on whether catchers have an effect on whether a pitch is called a strike or a ball (look for it tomorrow or Friday at Beyond the Box Score </shameless plug>), I realized I didn’t know what replacing a ball for a strike was really worth. A Google search turned up some information as to the run value of a given count, but not the information I was looking for. So I took a little detour from my planned study and decided to calculate the value myself.
Using data found in this thread at the Book Blog and the 2006 Major League splits from Baseball-Reference, I determined the value of a ball and a strike for every count (from the point of view of the pitcher). The difference between those numbers is the value of switching a ball to a strike at each count. Then I took average of the values at each count weighted by the number of plate appearances at that count to get the final number of .161 runs.
In the interest of full disclosure, and for those who might be interested in the breakdowns, here’s the data.
|B||S||WOBA||LW||RV Ball||RV Strike||RV B->S||PA||Weighted RV|