THE BOOK--Playing The Percentages In Baseball

Thursday, February 28, 2008

Should Ichiro steal more?

There’s a discussion over at USSM as to whether Ichiro should run more.  I write the following at post 91:

While I am pleased at the use of LI, it is actually not the most appropriate thing to use.  For those who don’t know, the LI can be found here:

http://www.insidethebook.com/li.shtml

If you go to the bottom of the 9th, tie game, man on 1b and 3b, 2 outs, you will see that the LI is very high.  However, it would be foolish for the runner on 1B to steal, because his run means nothing at all. 

What you really care about is the breakeven point, and for that you need win probability charts, like this one which gives you the chance of winning in our case here at .686

with a .16 win drop on a cs

and no change in increase on a sb (difference negligible due to sample size).

A SB will add nothing to the chance of winning, while a CS will decrease it drastically (sends it to extra innings), making the breakeven point pretty much 100%.  No one should try to steal in that case.

I go through all this in The Book, for those interested.

So, don’t look toward LI, but changes in win probability due to sb and cs, and calculate breakeven points from that.