Batting average (BA) has always been one of the most important statistics in baseball. But for a while now, on-base percentage (OBP) has come into vogue as an even better metric to measure hitting. So which metric is better: on-base percentage or batting average?
First off, we should ask ourselves what we mean by the word “better”. It is possible that two different metrics can be “better” at capturing different aspects of the game of baseball. Maybe one isn’t better at all – maybe they are just different.
Then we will actually compare on-base percentage to batting average as baseball analytics to determine which metric might truly be said to be “better”. By the end of this article, you should have a fuller understanding of why on-base percentage is actually the better metric.
Can Baseball Metrics Be Better and Worse?
The truth is, some baseball metrics are not better or worse than others. They just capture different aspects of the game. For example, batting average and stolen bases are two offensive stats that tell you about different parts of the offensive game: hitting the ball for a hit versus stealing a base. Each metric is not better or worse than the other, it’s simply that they measure different aspects of a baseball player’s performance.
And another thing: for most baseball fans, a stat isn’t only supposed to convey information about a player’s performance. It should also be easy to understand. Major League Baseball doesn’t want to ask its fans to do rocket science just to understand what’s happening on the baseball field.
Metrics like batting average and stolen bases are easily digestible to anyone who has a basic grip on simple math and basic stats. Which is most of the adult population of the United States. So, batting average and stolen bases can both be said to be good metrics in this way.
People who write about baseball for a living have to balance these competing needs: to help them accurately understand the performances of baseball players while also using metrics that are relatively easy for most people to understand.
If two metrics are both pretty easy to understand then it is pretty evident that the better metric would be the one that better captures the true performance of a baseball player in some aspect of the game of baseball. So which one is better: batting average or on-base percentage?
Understanding Batting Average
Batting average is an easy stat for most baseball fans to understand. It measures the number of times a batter gets to at least first base on a hit – at least a single – divided by that player’s official at-bats. To take a real-world example, New York Met Jeff McNeil led all of MLB in batting average in 2022 with a BA of .326.
To calculate that batting average, we simply take McNeil’s total number of hits – 174 – and divide it by his total number of at-bats – 533. And 174 / 533 = 326 – check it on your digital calculator if you do not believe me. The more hits you have relative to your total number of at-bats, the higher – and better – your batting average will be. So it’s fair to say that all things being equal, a baseball player with a .326 batting average like Jeff McNeil is a better hitter than a baseball player with a .236 average.
But that is not where the story ends. Because when a batter comes to the plate, it’s not just a binary result between a hit and an out. A lot of other things can happen including:
- a walk
- a double
- a triple
- a home run
- a hit-by-pitch
- a sacrifice fly
None of these different outcomes gets incorporated into a player’s batting average beyond being recorded as either a hit or an out. But they should still be measured in some way.
In order to capture such information, we need statistics designed to do so. On-base percentage is a metric that was created in order to measure how often a player gets on base rather than only when he does so via a hit. So while this still leaves out lots of information about things like doubles and triples, it does tell you a lot more of the story than batting average by itself. Let’s take a closer look at on-base percentage now.
Understanding On Base Percentage
On-base percentage is a baseball analytic that is designed to capture how often a baseball player gets on base. Now, there are three different ways a batter at the plate can get on base: they can get a hit, they can earn a walk, or they can get hit by a pitch.
On-base percentage incorporates all three of these outcomes. It adds together a player’s total hits (singles, doubles, triples, etc.), walks, and times they’ve been hit by a pitch, and divides them by a metric called “plate appearances”.
Plate appearances are different than at-bats, because walks do not count as an official at-bat, and neither do hit-by-pitches. But these still count as real times the player came to the plate and achieved one of these various outcomes. So whereas an at-bat only takes stock of hits and outs, a plate appearance takes into account hits, walks, hit-by-pitches, sacrifice flies, and outs.
To calculate a player’s on-base percentage, simply add together a player’s hits, walks, and hit-by-pitches, and then divide this number by that player’s total plate appearances. In other words: obp = (hits + walks + hit by pitches) /plate appearances (hits + walks + hit-by-pitches + sacrifice flies + outs).
To again take New York Met McNeil as an example, we would add his hits (174), walks (40), and hit-by-pitches (11) and then divide this number by his total plate appearances 589, or McNeil’s OBP = (174 + 40 + 11) / 589 = .382. Incidentally, this is a very good on-base percentage for a Major League baseball player.
But Which Is Better: OBP vs. Batting Average?
Now that we have a solid grasp on both metrics, it is fair to ask which metric better captures the performance of a batter: batting average or on-base percentage. But how do we know which metric better does its job?
To do so, we need to understand the main goals of a hitter and of the offensive component of a baseball team. Of course, the ultimate goal of any baseball game is to win the game. And the team that scores the most runs is the team that wins the game. So scoring the most runs is essential.
To understand which baseball analytic is better, we should consider which one correlates with a higher number of runs scored. In other words, does a higher batting average or a higher on-base percentage lead to more run-scoring?
In theory, you might think that hits are more important than walks. And in a way, you are right. Hits are slightly more valuable than walks. Why? Because when you earn a walk, you only get one base as a rule. But when you get a hit, you have a potential for other outcomes: maybe the batter legs out a double on a tough throw, or an infielder makes a throwing error allowing the hitter to get all the way to third base.
So it is fair to say that hits are a little bit more valuable than walks. But does that mean batting average is a better metric than on-base percentage? The research says no. To understand why we should consider baseball’s scarcest resource: outs.
On Base Percentage and Not Making Outs
When you think about it, runs are an unlimited resource in baseball. After all, if you keep getting hits, you could theoretically score an infinite number of runs – or at least keep scoring them until all the players are dead of natural causes.
Outs, on the other, are quite finite. In fact, in a regular nine-inning game, we know exactly how many outs there will be: 27. Always. Now, every time you make an out, you bring the end of the game one out closer. But also, every time you make an out, you have fewer opportunities to add runs. After all, if you get a hit or a walk, you are now on first base with no additional outs recorded, and you have a new chance to bring that runner home to score a run.
But here’s an important fact to consider: every time a batter makes contact and hits the ball in fair territory, that batter only has a 30% chance of getting a hit. That’s pretty low! The other 70% of the time, they make an out on a ground ball, caught fly ball, caught line drive, etc.
On the other hand, if a batter walks, they get on base 100% of the time. It is not possible to walk and make an out on the same plate appearance. So when it comes to hits versus walks, you are talking about a 30% chance of getting on base and having a chance for that runner to score, and a 100% chance of getting on base and having a chance for that runner to score. And a 100% chance here is a lot better than a 30% chance.
So while a hit is better than a walk by a little bit, walks are MUCH better than outs. So not making an out becomes much more important than whether you get there via a walk or a single. Because getting on base is what allows you to have a chance for that runner to now score.
Why On Base Percentage Is Better
The higher a player’s on-base percentage, the fewer outs that player makes. And the few outs a player makes, the more runs they are going to help score, either by driving them in or scoring a run themselves. Plus, they have extended the scoring opportunity for the team and not hastened the end of the game as often as a player with a lower OBP.
For that reason, it is also true that OBP correlates higher with runs scored than batting average does. In other words, improving your on-base percentage will help your team more than improving your batting average.
Since the goal of the offense is to score runs, and on-base percentage is a better measure of how many runs a player will help create than batting average, on-base percentage is better at measuring offensive production than batting average.
That doesn’t mean that batting average is useless or tells you nothing. Getting hits has value, and from a pure hitting perspective, a .300 hitter is a good singles hitter. It’s just that this particular metric doesn’t tell you much else beyond how good a player is at hitting singles, only one piece of the offensive puzzle.
So, if you are trying to evaluate the quality of a player or a team, using on-base percentage is better than using batting average.
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