This article is part of our The Z Files series.
One of the pitfalls of having more data to use is more people are misusing data. Something I have talked about previously is the notion of stability points and how they don't mean what many think they mean. Well, I'm back with my annual warning, but this time I've come with backup. In addition, I'll take a look at how the 2021 baseball is playing, which may not be as expected (or reported, at least very early).
A stabilization point is loosely defined as when a particular metric becomes useful. I'll spare the next level algebra, but one way to look at it is the stabilization point is the sample size where half is a result of the player's skill and half is happenstance.
When I first read about the concept many years ago, it appeared incorporating stabilization points in rest-of-season projections could be cutting-edge analysis. For example, the stabilization point for strikeouts is around 60 plate appearances. Imagine being able to make salient adjustments to player expectations only two weeks into the season! Yeah, pretty cool.
As an example, if I projected a 30 percent strikeout rate for a batter and after 60 trips to the dish, he was fanning 20 percent of the time, I'd adjust my rest-of-season strikeout rate to 25 percent. The idea is there was a 50/50 chance the players new 20 percent mark was real, so I averaged it with my initial projection. I framed the analysis as a guide to identifying