📂Sabermetrics

Definition of At-bats in Baseball

Definition ¹

The term At Bat, abbreviated as AB, refers to the number of times a batter

• hits a ball,
• reaches base on a fielder’s choice,
• reaches base on an error, or
• gets out (excluding sacrifice hits).

Theorem

• [1]: The equation for a batter’s plate appearances (PA), at-bats (AB), walks (BB), hit by pitch (HBP), sacrifice bunts (SH), sacrifice fly (SF), and reaching base due to batter or 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 true for plate appearances (PA) [../2190], at-bats (AB) [../2192], and hits (H) [../2194]: $$ \begin{align*} H \le AB \le PA \\ 안타 \le 타수 \le 타석 \end{align*} $$

Explanation

Fielder’s Choice and Error

A Fielder’s Choice is when a fielder chooses to attempt an out at a different base instead of trying to put out the batter-runner, allowing the batter to reach base safely. Though it does not count as a hit, it counts towards at-bats, thus lowering batting and slugging percentages.

An Error is when a batter reaches base due to a misplayed ball that should have resulted in an out.

Sabermetrics

These concepts are key records affecting batting average, slugging percentage, on-base percentage, and further, the OPS calculation. It’s advised for those unfamiliar with baseball to use theorem [1] for calculations since Fielder’s Choices and Errors can be confusing. In the Korean League (KBO), the definition excludes walks, sacrifice hits, and reaching on batter or runner interference from finished at-bats.²

Differences Between Plate Appearances and At-Bats

To those unfamiliar with baseball, both might confusingly look like ‘타ㅅ’. Simply put,

• Plate appearances are the number of times a player stands at the plate regardless of the bat’s involvement,
• At-bats are the number of times the bat physically contacts the ball.³

Since one cannot have an at-bat without standing at the plate, it is impossible for at-bats to exceed plate appearances. If a beneficial hit is considered a hit, then the inequality stated in theorem [2] applies. $$ 안타 \le 타수 \le 타석 $$

It is known that explaining these records through specific game situations to novices has significantly less effect. Instead, we will understand the following records according to the mentioned inequality:

• (1) 4 plate appearances 3 at-bats 3 hits: In four chances, seized three opportunities, and all three contributed positively to the offense, which is a good record.
• (2) 5 plate appearances 1 at-bat 2 hits: Implies that a single swing sent at least two balls flying, which is an impossible record.
• (3) 5 plate appearances 2 at-bats 1 hit: In five chances, seized two opportunities, and among them, one resulted in a hit, making the inequality properly hold true.
• (3) 3 plate appearances 0 at-bats 0 hits: Despite being given three chances, not managing a single hit thus contributing nothing to the offense, which is a bad record.