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April 18, 2005

Minor League Batting Averages on Balls in Play

Does Voros' Theory Work on the Farm?

by Clay Davenport

At feeds, signings, and any other meeting I happen to attend, it is clear that Voros McCracken’s observations on pitching and defense still generate intense disbelief from many, if not most, baseball fans.

First of all, let us be clear on what Voros actually said. He initially claimed that pitchers have no control over whether balls in play turn into hits or outs; after more work, he refined his claim to say that the differences between major league pitchers is small, much smaller than commonly believed, and small enough to be insignificant information. It is convenient shorthand--an exaggeration, if you will--to continue with the original idea of there being no differences, and that the differences we do see can be attributed to luck. Here at BP, we’ll describe a pitcher as being "hit-lucky," for instance; admittedly, from the data, you would have a hard time showing that it isn’t luck.

Quite a few people have challenged Voros’ original article and subsequent follow-ups, with the best one probably being Tom Tippett’s. However, even Tom’s article still shows that most pitchers, indeed, have almost no effect. This still runs so contrary to most people’s expectations that some more explanation is in order.

First, I have to say that most people are interpreting the proposition in light of their own direct playing experience--which, for the vast majority of us, does not extend beyond Little League or perhaps high school baseball. They know pitchers have some ability to be harder to hit because they have experienced it themselves, and no statistics can convince them otherwise. The trick here is to understand that major league baseball is a different game from what you played in high school. Some of the things we talk about on BP--a strikeout is no worse than any other out, for example--are not universal baseball truths, but are only true when the skill levels involved are at or near major league levels. A strikeout is worse than other outs because it doesn’t advance a runner and doesn’t give the other team as much of a chance to make an error; it is better than other outs because it doesn’t give the other team a chance to make a double play. You have to get somewhere in the high minors before the ability of the defense is high enough, both to turn a double play and to not make errors, to tip the scales from strikeouts being a really bad event to being no worse than other outs.

Hits per ball in play may be another one of those truths. Suppose that there is a clear ability to make batters hit a ball weakly, and that teams can recognize it; clearly, this would be a valuable ability for a pitcher to have. Other things being equal, it would give a pitcher an advantage, like height in the NBA. Assuming that teams can recognize it and select for it, you would produce a major league where the selected population is better than its selection group--just as NBA teams are taller, on average, than NCAA teams (its principal recruiting pool), major league pitchers should be better than minor league pitchers, and you should be able to demonstrate a weeding out of the less able. Reaching the major leagues is a sensational example of Darwinian survival.

So: do they? The first part is easy to answer--do major league pitchers give up hits (per ball in play) at a lower rate than minor leaguers? And, ideally, does it go down in a steady progression with minor league level? At first glance, the answer is, "sort of."