Introduction and Hypothesis

One of the longest standing tenets of sabermetrics, stemming from Voros McCracken’s seminal 2001 work on DIPS (Defense Independent Pitching Stats) theory, is that pitchers ought to try for strikeouts rather than focusing on inducing weak contact. McCracken asserted that pitchers have little control over the quality of contact they allow. However, they do control if they strike the batter out (good) or walk him (bad) or allow a home run (even worse). Put another way, McCracken found a strong negative correlation between a pitcher’s strikeout rate (K%) and his runs allowed per nine innings (RA9). It is a simple logical step from here to conclude that pitchers ought to try to strike batters out.

Or is it?

Might McCracken’s DIPS observations only hold as long as pitchers are trying to generate weak contact? If they begin to focus solely on strikeouts, might this observed correlation weaken? Might we find more pitchers who are able to generate strikeouts but are not particularly successful at preventing runs?

As an analogy, consider a farmer whose goal is to get a big harvest of high-quality crops. To this end, he regularly waters and fertilizes his plants. He hires a consultant who does some studies and points out that fertilizing is closely correlated with the quality and quantity of the harvest. As a result, the farmer shifts all of his efforts to fertilizing and ignores watering altogether. Clearly this is not the best strategy. In the same way, might a pitcher be hurt by focusing on strikeouts and ignoring the quality of contact his pitches will generate if the batter does make contact?

With this in mind, might we, as analysts, in fact be affecting the very phenomena that we’re observing? Read the rest of this entry »