THE BOOK--Playing The Percentages In Baseball

Thursday, January 13, 2011

Channeling your inner Leverage Index

Marty Noble:

The save rule needs to be amended in a way so we can measure the degree of difficulty or the challenge involved. Saves ought to be weighted, i.e., a save achieved in a three-run game would be worth one point, a save achieved in a one-run game would be worth three points, a two-run save would warrant two points.

More could be done involving the number of outs required, inherited runners vis-a-vis the score. But simply weighting the saves, by itself, probably would produce a greater disparity in the save-points totals than the disparity that exists now when 12 closers have between 35 and 45 saves. So we’d likely see a conspicuous difference between the 33 saves Closer A achieved and the 35 Closer B earned.

Leverage Index in the top of the ninth to start the inning:
up by 3: 0.8
up by 2: 1.6
up by 1: 2.9

And in the bottom of the 9th:
up by 3: 1.0
up by 2: 2.0
up by 1: 3.6

Basically, this is the pattern that Noble is proposing, and it is captured by Leverage Index (LI) already.  He further suggests outs and runners on base without elaborating.  But, since we’ve already been able to match his needs on bases empty 0 outs with LI, presumably he can easily buy in on what the rest of the chart shows for runners on base and outs.

LI is basically a quantification of your qualitative feelings on how much impact a certain context has.  I think this is how you can hook in someone like Noble, to show him that we already have a process that matches exactly what he’s thinking on things he’s come to a conclusion on, and so, he should be able to buy in to the rest of the stuff he hasn’t made a decision on yet.

If he insists on integers to assign points (and presumably capping it), that’s fine, we can come up with some basic rules based on half-innings, score, runners, and outs.