Revisiting a Win Shares Issue
I recently received a question from a reader in the “Hey, Bill” section:
I'm reading the Win Shares book again and am wondering if you (or someone) has solved the "Why 52" issue about the relative value of a run saved or added.
Trailbzer
For those of you who might miss the reference, this refers to the decision, in designing Win Shares, to allocate 52% of the credit to pitching and defense, 48% to hitting and baserunning. I wrote an article saying, in essence, “Yes, I know this doesn’t make sense, but it seems to be necessary. I’ve tried and tried to make it work with a 50/50 split between offense and defense, and it just doesn’t work.”
It turned out that this was the result of a simple and stupid error on my part, having to do with how I handled pitchers’ hitting. I originally set up the analysis so that 50% of the credit would go to run creation, 50% to run prevention. However, hitting by pitchers was kind of a leftover, and I decided to give credit for pitchers’ hitting as if it was part of their pitching. In other words, suppose that there were two pitchers who were otherwise the same, except that one of them created five more runs than the other as a hitter. I decided that “five runs added as a hitter is the same as five runs saved as a pitcher”, so I simply adjusted their runs saved as a pitcher for their runs created as a hitter.
On a certain level this was not illogical, but what I failed to see until a year or two after I finished the Win Shares book was that this had screwed up the 50/50 split. I knew that SOMETHING was screwing up the 50/50 split, but I couldn’t figure out what it was. Pitchers’ hitting is a significant factor in the game. . .something like 3-4% of the game, when pitchers hit. When you move that 3-4% to the wrong side of the ledger you have too many parts on that side of the ledger.
When I started designing Win Shares and Loss Shares I went back to the beginning, and I handled pitchers’ hitting in an entirely different way. Early on in the design of Win Shares and Loss Shares I realized that, using 52% for pitching and defense, I had too many Win Shares going to pitching and defense, and I needed to move it back to 50%. So then I asked myself, “Well, what am I doing different here than I was before, that caused this problem to go away?”
Just a silly design mistake on my part.