Updated: April 30, 2021

Bat Fitting

We have nightmares about a question we get all the time.

Here it is:

How good is that bat?

For a site built on the idea that we can help people fitting the right bat, you’d think we’d welcome that question.

We do. Yes. But we also don’t. No.

The reason we do like it is that we think it’s a reasonable question to start with. I mean, if you don’t know much about bats, what else could one possibly even ask?

The reason we hate it is it leads us into a 20-minute diatribe about bat performance. It ends when the questioner’s eyes glaze over; they hum and ha a few times and then happen to be urgently called on their cell phone for a “must take” call.

I don’t blame them.

They were asking what seemed like a simple question and were hoping for a relatively simple answer.

“It’s good.”

“Maybe not the best.”

“My boy likes it.”

You know, something like that.

But we suffer from thought-too-long-about-bat-performance-itis. It’s a brutal and incurable condition.

We’ll try and answer that for you here. Seriously, turn your cell phone off.

Identifying the barreled zone.

To start answering if the bat “is good,” we must establish what we mean by bat performance.

We can break bat performance into two parts: barrelled and consistency.

  1. Barrelled is the official MLB term for a ball hit with enough exit speeds and launch angle to maximizes the chances of getting bases.
  2. Consistency is how often we “barrelled” up a game pitch.

In other words, the bat that barrels a ball with the most consistently is the best.

What they are asking

‘Compared to every bat on the market before and since, does this particular bat barrel up the ball with more consistency than most other bats?’

What they aren’t asking (we think)
  • Does this bat have the best exit speeds?
  • Does this bat have the biggest barrel?
  • Is this bat the best value?
  • Would you buy this bat for your son?
  • Does this bat have the biggest sweet spot?
  • Is this bat’s swing weight the right swing weight for my player?

The question compound in difficulty when we realize that the answer is hitter-dependent.

Take wood bats, for example.

Barreled Balls per plate appearance

Here’s a list of MLB players ranked by the number of times they “barrelled” up a ball per plate appearance. (We could improve this metric by removing walks from PA, but it’s good enough for now).

Barrelled Balls Per Plate Appearance (2021)
  1. Ohtani comes in at #1–he barrels up balls in 16.1% of his plate appearances.
  2. Nelson Cruz at 15.9%.
  3. Rafael Devers at 14.9%
  4. Franmil Reyes at 14.9%
  5. Bryce Harper at 13.5%
  6. Jess Winker at 13.3%
  7. Matt Olson at 13.2%
  8. Ronald Acuna Jr. at 12.7%
  9. Mike Trout at 11.9%
  10. Kyle Seager at 11.9%

Therefore, the best BBCOR bat on the planet is the Asics Goldstage (aka Shohei Ohtani’s bat.)

Eat your heart out, Demarini.

There’s a lot of buzz about what’s the best wood bat.

But what other proof of the best wood bat would anyone ever need but by the unequivocal documentation that the bat that hits the ball the hardest at optimal launch angles and with the most consistency is the Asics GoldStage?

Ha. That’s funny, right?

Because no one actually believes that the Goldstage is the best bat.


Because Ohtani is the one swinging it, and we all feel confident he could outhit half the league with a broomstick.

So, we’ll ask you about the Asics Goldstage, “is that bat good?”

Clearly, it is good for Ohtani.

But when we ask, “is the bat good” were really asking “is the bat good for me.”

The bat’s ‘goodness’ is determined by the ability of the individual using it.

This principle of bat fitting is why algorithms that determine the right bat are rarely useful in determining the right bat for you. It’s also why watching a pro hit might be fun, but it’s rarely useful insight on the best bat for you—especially if you’re not a pro (yet).

In theory, devising a formula that comes up with a good bat for you is painfully difficult—dare we say impossible.

But the goods news is that, in practice, it’s easier.

Because, well, it’s practice.

And that’s our answer for, “is that bat good.”

We can tell you the swing weight, what some other kids did with it, how much it costs, and why you might want to buy last year’s model.

But, “is it good?”

Is it GOOD?


You tell me.

What is MOI

Another note we thought we’d put here is about the Mass Moment of Inertia or MOI.

In baseball and softball bats, Mass moment of inertia is the force required to swing a bat. It’s known more often by its name, swing weight. The heavier the swing weight, the more ‘end-loaded it feels, and the higher the MOI.

We have an entire article on the ideas of MOI, swing weight, and scale weight. Based on your question, you will likely find it helpful.

Scale Weight vs Swing Weight

We think our bat size chart would answer most of your questions for bat sizes by age in terms of bat sizing.

How can you use MOI to help fit bats to players? We aren’t hitting coaches, so not sure we can answer that entirely. But, it seems natural that you can use the MOI of one bat to see where it falls compared to others. If a hitting coach thinks a lighter or heavier bat might be useful, they might recommend based on the rankings of that list.