Luck has
been the explanation whenever a pitcher has a significantly lower ERA than his
FIP. There are two statistics where luck plays a huge role, BABIP and LOB%.
Using Steve Staude’s pitching stat correlation tool, we can see that BABIP only
has a correlation of 0.156 from one season to the next, while LOB% has a
correlation of 0.205, for pitchers with a minimum of 30 innings pitched from
2007 to 2013. These numbers are much lower than the correlation of K% or BB%,
suggesting that a large portion of BABIP and LOB% are subject to random
variation and independent of a pitcher’s skill. However, the correlation is not
0. They are not completely random, and a pitcher can still play a small role in
controlling their BABIP and LOB%. Many writers, including Steve, have tackled
the issue of BABIP using batted ball data. In this article, I will be
estimating a pitcher’s LOB% for the current season. This is not supposed to be
a predictive stat, but a descriptive one. Think of it as FIP. While FIP
estimates the pitcher’s ERA using strikeouts, walks and homeruns, xLOB%
estimates the pitcher’s LOB% given his other pitching statistics for the same
season. I will be introducing pLOB% in the next article, which attempts to
project LOB% of a pitcher for the following season.
