Though not the most intuitive statistic, batting average was a gold-standard statistic for many decades, and is still considered important today.
In short, batting average measures how often someone gets a hit among all situations where a hit was “possible”. This requires us to differentiate plate appearances and at-bats.
A plate appearance is the most general event for a batter. As the name suggests, every time a batter steps to the plate they are participating in a plate appearance. Regardless of the outcome, their plate appearances increase by 1 each time they face a pitcher.
An at-bat is a slightly more limited set of factors. If the result of the plate appearance is a walk, hit-by-pitch, or sacrifice hit (e.g. a bunt intended to let another runner advance a base), it does not count as an at-bat. Everything else though — hit, error, strikeout — counts as an at-bat. In other words, every situation where the batter made an attempt to reach base via their bat counts as an at-bat.1We consider a walk or HBP as the batter not having an opportunity to use their bat. A sacrifice is exactly that: the batter sacrificing their chance of getting a hit to let a runner advance.
Now, take the number of hits a batter has, and divide it by the number of at-bats. That is the batting average (BA or AVG, depending on your source).
\text{BA} = \dfrac{\text{Hits}}{\text{At-bats}}It’s a statistic that rewards batters who get on base by hitting the ball, arguably the entire point of baseball. That is why it was and continues to be a treasured statistic. In fact, the player in each league who finishes the season with the highest batting average wins the batting title.
Batting statistics require a batter to be qualified through a sufficient number of plate appearances to be in consideration for winning any statistical award. The official rule is that a batter needs 502 plate appearances across the 162-game regular season, which comes out to about 3.1 plate appearances per game the team plays. They switched to using plate appearances in 1957 instead of their previous rule of 400 at-bats: no need to unfairly or accidentally punish someone who gets walked a bunch.
So you have a baseline, these days we consider a .300 BA the baseline for a very good hitting season.
Here are a few interesting batting average statistics:
- Joe Mauer of the Minnesota Twins is the catcher who won the most batting titles, with 3.
- The last qualified player to bat over .400 in a season is Ted Williams, with an average of .406 in 1941.
- The player with the best career batting average in the 2nd inning with at least 100 plate appearances is Eddie Collins, with a .437 average.
Continue to Day 2 – On Base and Slugging Percentage
- 1We consider a walk or HBP as the batter not having an opportunity to use their bat. A sacrifice is exactly that: the batter sacrificing their chance of getting a hit to let a runner advance.