A Deep Dive to the Bottom of the Strikezone

This article is by guest author John Storey

We’re living in an age where strikeouts are king. There’s no denying the rapid ascend in strikeout rate, a relative disregard for lack of contact in exchange for the power upside a little extra recklessness provides. Few people will question the efficiency of power optimization and swing plane alterations, and those few would be promptly silenced by anyone with a run expectancy matrix. 

A less publicized strikeout trend is not the number of strikeouts, but in the type of strikeouts pitchers are hoarding. Since the very dawn of statistics’ stronghold on baseball, the rate at which hitters head back to the bench after watching strike three has been tumbling.

The matter of who is responsible for the jump in strikeouts – never mind swinging strikeouts – is anyone’s guess. As both hitters and pitchers change their fundamental approaches they forever alter outcome trends, particularly strikeouts. Pitchers have changed where they’re throwing what pitchers, no longer bashfully avoiding tempting batters with high heat – and it works. Meanwhile, hitters now curse their little league coach who insisted on a level swing. Thus, it’s reasonable to assume that both parties are instrumental in the declining rate of actionless strikeouts.

Speaking of actionless strikeouts, it’s important to accentuate a disclaimer: While the nature of swinging and called strikeouts are not always indicative of the plate appearance’s plot, merely defined by their rearmost event, they remain relevant. Despite discredited definitions, the merit of the distinctions is far from lost. 

Consider the third strike, the titular strike. The batter makes a decision with more consequence than the sum of the decisions preceding it. It would make sense that in an environment where hitters’ propensity to strikeout swinging is higher, the frequency with which they walk would suffer. It’s not an especially strong correlation, (r = 0.654), but a correlation nonetheless. Derived from a common cause, hitters are, to make a blanket statement, more aggressive in our contemporary game.

In light of an intention to evaluate or develop an auxiliary data point with which to grasp a player’s profile, the manner in which batters strikeout is critical. If batters can fend off established and predictable methods of striking out, rising against conformity they may be inherently patient hitters, or possess a strong ability to pick up on pitches. This normality is generated by pitchers’ habitually consistent approach to striking hitters out. Reviewing strikeout heatmaps, these methods become apparent:

The pitch and strikeout type breakdowns for some perspective:

The heat maps show how hitters who strikeout looking, repeatedly do so around the bottom of the strike zone. The map representing all swinging strikeouts presents some diversity. Its called strikeout counterpart, not so much. Thus, this trend appears to be a reasonable benchmark. Hitters most reliably strikeout looking in and around the bottom of the strike zone. Not only is this concentrated (less diverse than the locations of swinging strikeouts) but as noted before, it is an increasingly scarce event, highlighting some intrinsic difference separating hitters who do not follow this normal. Maybe that makes it less reliable, more random. As an extreme, is one’s number of home run robberies an indication of defensive capability? Nonetheless, the amount of data is sufficient and reliable for a player who’s played remotely near a full season. Measuring that player’s ability to maintain control in a time of just the contrary should render an enlightened player profile. 

The data simply shows a hitter’s propensity to strikeout looking at pitches which are situated in territories that conventionally fool their colleagues. Aggressiveness is one takeaway here. Probably more significant and relevant is the measure of a hitter’s ‘eye’. Pitches at the bottom of the zone are more difficult to read, never mind evaluate. Specific determinants aside, the principle still applies. This shouldn’t be used as a direct measure of determinants, but rather used to better understand the pre-existing array of plate discipline metrics, perhaps offering insight into how indicative of one’s innate abilities those existing fundamental measures are. And ultimately, reveal what situational noise exists. 

To deduce that player’s motion relative to the mean is not to appreciate his performance, value or impact. It’s merely another piece to the puzzle in acknowledging who a player is as a hitter, what his tendencies are and how they can be remedied, exploited or developed. 

All data sourced from baseball-reference.com and baseballsavant.mlb.com.