Minors BABIP Musings: Part 1

In sabermetric circles, we often discuss batting average on balls in play (BABIP) as a function of luck that regresses to the mean for pitchers. It is commonly accepted in saber theory that hitters tend to have more control over their BABIPs than pitchers do. That makes intuitive sense, as it relates to a hitter’s speed and ability to consistently square the ball up.

Hitter BABIP is a fairly crucial stat. After all, batting average can be broken down this way:

AVG=(HR/AB)+((BABIP*(AB-HR-K))

Batting average isn’t the all-important statistic many believed it was a decade ago, but it sure helps, and it’s pretty difficult to post a good batting average without at least a decent BABIP.

We talk a lot with respect to pitchers that BABIP regresses to around .300. In MLB last year, non-pitchers had a total .297 mark, so .300 is a pretty good estimate.

We can see that pitcher BABIP does indeed cluster closer to that area than hitter BABIP does. For example, of the 145 pitchers to throw at least 100 innings in MLB in 2011, none had a BABIP higher than .341. By contrast, 18 of the 265 hitters that received over 300 plate appearances posted BABIPs above .350.

With a .350 BABIP and average home run and strikeout rates, a batter will hit right around .300. Indeed, all but one of the 18 batters with .350+ BABIPs hit .285 or better.

We often talk about minor league environments in terms of run scoring in certain leagues (the Cal League and PCL inflate run scoring, for example), but rarely do we look at an entire level of the minors as a whole when it comes to the statistical environment, nor do we consider the minors as a whole. We generally assume that the statistics are distributed somewhat similarly to the majors, or at least, it’s easy to fall into the trap of assuming that. There’s no intuitive reason to believe that home run rates, walk rates, or the like are significantly different in the minors than the majors (though they may be; I didn’t look them up).

There are, however, overwhelming differences in one area–how easy it is to post a high BABIP. Here’s a quick breakdown of the number of hitters (300+PA) at each level that posted BABIPs of .350 or above. For short-season levels, I used the “qualified” threshold instead of 300 PA.

MLB: 18 of 265 (6.79%)
AAA: 54 of 225 (24%)
AA: 44 of 235 (18.72%)
Hi-A: 41 of 234 (17.52%)
Low-A: 42 of 242 (17.36%)
SS-A: 39 of 129 (30.23%)
RK: 108 of 268 (40.30%)
Minors*: 236 of 1245 (18.96%)

*For the minors total, it was all hitters with 300+ PA. That obviously excluded many short-season hitters, but it also included a lot of players that split their time between multiple levels and never accumulated 300+ PA at any one stop.

That is a significant portion of minor league hitters, even at the upper levels, that seem to heavily rely on a BABIP ability that won’t translate to the majors.

Take Cubs outfielder Brett Jackson, for example. He’s hit .292 in his minor league career despite striking out 23.9% of the time, mainly because his BABIPs go like this:

Short-season-A, 2009: .418
Low-A, 2009: .356
High-A, 2010: .395
Double-A, 2010: .352
Double-A, 2011: .323
Triple-A, 2011: .402

Now, Jackson’s a patient, selective hitter who swings at good pitches and tends to make hard contact; he also has the speed to beat out the occasional infield hit. But that strikeout rate–which swelled to nearly 30% in Triple-A–looks fairly prohibitive, his power isn’t off-the-charts good, and there is no way he’s going to post .402 BABIPs in the majors. Ichiro, considered the master of BABIP, has a .351 career mark, and only topped .355 in four of his 11 seasons. To project Jackson–or any minor leaguer–to do better than that is irrational, in my mind.

And clearly, this isn’t an uncommon occurrence, borne out by the fact that nearly a quarter of Triple-A regulars are in .350+ territory. Obviously, these guys aren’t likely to sustain their performance, but what exactly happens? I’ll delve into some case studies in Part 2, which will be up either later today or tomorrow.

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