The main feature of randomness is independence from initial conditions—the outcome of an in-park batted ball cannot be fully predicted from the interaction of the pitcher and batter because neither participates in the play after contact (except in limited roles as fielder and baserunner). However, the randomness in BABIP is not itself random, and can be characterized in terms of hit probabilities: about 0.59 for a well-hit ball, about 0.19 otherwise. We can predict the likelihood that an in-park batted ball will result in a hit based upon the velocity generated at contact.

The BABIP phenomenon, then, is really a two-stage action. The first stage is the process of putting the batted ball in play; the second stage is the outcome that results from luck and defense. The dividing line is the moment of contact. The pitcher has no control over the second stage, the outcome, except as a fielder. But before contact, in the first stage, the pitcher wields substantial control over the batter’s attempt to hit the ball hard. The pitcher establishes his control through various inputs, including pitch type, spin, speed and location; pitch balance and sequence; deception and command; working the count; and the hitter’s history of previous plate appearances facing the pitcher.

In this model of BABIP, most of the luck occurs after contact in a chance process in which batted ball speed determines the probability of an outcome. BABIP is deterministic but random. By using strikeouts and home runs, which are 0% and 99.5% well hit respectively, DIPS admits pitcher control over the extremes of contact. Strikeout and home run rates serve as rough-and-ready proxies for a latent contact hardness variable that manifests as batted ball velocity. Home run is the only official batted ball stat about which we can reliably infer contact hardness.

Outcomes of in-park balls in play appear random because no ordinary records are kept about how well they were hit. David Gassko’s study detected a predictive relationship between strikeouts per game, home runs per game and BABIP. An explanation for these correlations might be that strikeout and home run rates approximately represent a pitcher’s tendency to allow hard hit balls, a tendency that persists as a skill.

If major league pitchers are skillful at controlling whether batters make hard contact, and BABIP becomes less random in a data-rich world that includes batted ball velocities, then it follows that pitchers have more control over batted ball outcomes than previously thought. BABIP is a lucky number only to the extent that hits occur more or less frequently than predicted by the 0.59 and 0.19 hit conversion rates for well-hit and other batted balls. The pitcher controls his rate of well-hit in-park balls in the same manner as he controls strikeouts, walks, and home runs.

Chalking up BABIP as merely the result of chance outcomes does disservice to pitchers’ skill at preventing solid contact, which is the essence of pitching. Tossing a coin is chance, not skill, because you can’t control the result by how you flip the coin. Pitchers demonstrate skill in their control over the hardness of hitter contact, which indirectly but positively affects outcomes on in-park batted balls.
http://www.hardballtimes.com/main/article/a-different-look-at-babip/