📂Sabermetrics

Definition of Batting in Baseball

Definition

The number of times a batter stands in the batter’s box and completes their batting turn (in any way leaves the batter’s box) is called a Plate Appearance, abbreviated as PA.

Theorems

• [1]: The equation for a batter’s plate appearances PA, at-bats AB, walks BB, hit-by-pitches HBP, sacrifice bunts SH, sacrifice flies SF, and reaching base due to batter/runner interference $X$ is as follows: $$ \begin{align*} PA =& AB + (BB + HBP) + (SH + SF) + X \\ 타석 =& 타수 + 사사구 + 희생타 + X \end{align*} $$
• [2]: The following inequality holds for plate appearances PA, at-bats AB, and hits H: $$ \begin{align*} H \le AB \le PA \\ 안타 \le 타수 \le 타석 \end{align*} $$

Explanation

Sabermetrics

The accumulated stat of plate appearances signifies durability or reliability. A starting batter who finishes a game without being substituted usually takes 3-5 plate appearances. A decrease in the number of yearly plate appearances indicates that a key scoring player has underperformed, possibly due to slumps or injuries. Even players included in the roster but participating only as pinch hitters will accumulate plate appearances slowly.

Analyzing the entire league’s batting performance, a significantly small number of plate appearances for a player indicates insufficient batting sample. For example, if a promising rookie A hits a home run in their debut game and then misses the rest of the season due to injury, A ends up with an unusual record of a slugging percentage of 4 in 1 plate appearance. Regardless of A’s unlucky career, such data should be considered an outlier and requires appropriate action.

Origin

¹

The plate appearance itself refers to the plate where a batter hits the baseball. The English term Plate Appearance describes a batter appearing at the plate, and a plus one is added each time a batter completes their turn in any form. A batter who completes their plate appearance must be in one of the following three states:²

• Gets out.
• Reaches base and scores.
• Reaches base and stays on base.

Difference between Plate Appearance and At-Bats

To those unfamiliar with baseball, both may seem like ‘attempts’, which is why these records are often confusing. Simply put,

• Plate appearances count the number of times a person stood in position, regardless of the bat,
• At-bats count the number of times the bat physically contacted the ball.³

In baseball, if you don’t take a position in the batting box, there’s no use for the bat, hence at-bats cannot be more than plate appearances. If beneficial hits by the bat are called hits, then the inequality in theorem [2] holds. $$ 안타 \le 타수 \le 타석 $$

We know that explaining these records through specific game situations is markedly less effective for novices confused between plate appearances and at-bats. Instead, we will understand the following records according to the above inequality:

• (1) 4PA 3AB 3H: Given four chances, grabbed three opportunities and contributed to the offense in all, a good record.
• (2) 5PA 1AB 2H: One swing sent at least two balls flying, which is impossible.
• (3) 5PA 2AB 1H: Given five chances, grabbed two opportunities, and made one hit, properly satisfying the inequality.
• (3) 3PA 0AB 0H: Given three chances but failed to hit even once, contributing nothing to the offense, a bad record.