THE BOOK--Playing The Percentages In Baseball

Saturday, October 10, 2009

FIP Primer

Courtesy of Kincaid: parts 1 and 2:

Next, we determine the value of each event relative to the value of a BIP by taking the difference between each value and -.04:

HR 1.44
3B 0.34
out -0.23
BIP 0

This is the value of each event used in FIP. The formula above puts these weights onto a scale of per 9 innings; in other words, each weight is multiplied by 9, and then divided by IP. That gives you 13, 3, -2, and 0 as the weights per inning. So BIP are still there, just hidden in the formula. Their value is used to determine the weights given to each other event.

That’s the same process I use for wOBA.  Never realized it myself until now.