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Thursday, April 16, 2009
Are leadoff hitters overvalued?
Tom Hanrahan (pdf) seems to think so:
In summary, all Run Estimators overstate leadoff batters contributions to team runs scored. By about 10%. That ain’t small potatoes when figuring out what makes teams win.
He has his findings of when he put in a great hitter as a leadoff hitter (+74 runs), as a #3 hitter (+77 runs), cleanup hitter (+76 runs), #6 hitter (+69 runs), and #9 hitter (+63 runs). The same hitter, but in various slots, ended up having his team score that many more runs. This is his run impact. So, we can see that generally speaking, this great hitter should come out at roughly +74 runs or so.
Now, let’s say this hitter’s standard Linear Weights is +.11 runs per PA. As a leadoff hitter, he gets alot more PA, so he might have say 750 PA, while as a #5 hitter he’d have 72 fewer PA (or 678 PA). He ends up with .11*72= 8 more runs if you use his performance stats as a leadoff hitter.
Tom is totally right. Indeed, in Table 51 of The Book, I present the Run values by event, by batting order. Per PA, the run values of the leadoff hitter slot is about 5% below the average, while those in the #5 slot is 5% higher.
If however you look at it per game (rather than per PA), the run values of the hitters in lineup slots 1 through 5 is fairly constant (which explains almost totally why you want your five batters in the top 5 slots, and why mixing them up in there doesn’t really make much difference).
So, the solution is not to look at things in terms of per PA, but in terms of per game. When you look at Grady Sizemore and the other leadoff hitters with 750 PA, they do get an advantage in standard linear weights.
However, a play-by-play metric, like WPA / LI * boLI does not have this problem. And I agree with Tom that we should make the necessary adjustment. However, it will not come out to 10%. It’ll be +/- 5%.