🚨Red Alert 🚨 We Have New Statcast Data!

by EJ Fagan

May 15, 2024

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NOTE: The following comes from EJ Fagan's substack page and is shared with permission.

Please check out EJ's substack page for more great articles.

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Christmas came early this year.

Statcast dropped a rich new dataset yesterday: bat tracking.

The data are pretty simple. Statcast measured the speed of a player’s bat six inches below the end (the sweet spot). These data created their first new stat: bat speed.

We hear a lot about bat speed in baseball. Manny Ramirez, Gary Sheffield, Clint Frazier, and a bunch of other players had lots of bat speed. Or at least that was what we were told. I’ll be honest: I can’t tell the difference between an average bat speed and an excellent one.

But bat speed clearly matters. Basic physics holds that if you hit a thing faster, you impart more force on it. The ball should fly farther, all else being equal.

So who are the MLB leaders in bat speed in 2024?

Yep, it’s Giancarlo Stanton. By a mile. The gap between Stanton and O’Neil Cruz is 3 mph, or roughly the gap between O’Neil Cruz and the 28th ranked player. Stanton really is in a league of his own.

But it’s a fascinating list of players. About half are in the MVP contender bucket - Soto, Judge, Contreras, Adell, maybe Guerrero and Trout. Most of the others are hitters who struggle to make consistent enough contact to be as good as the hard contact they make. See: Giancarlo Stanton.

Bat speed would be a boring stat if there was a 1:1 correlation between bat speed and “good hitter.” In that case, it would just measure what we already know. Instead, we would describe the variable as somewhat orthogonal - it adds new information that we did not know from other offense stats.

For example, here are the lowest bat speeds in baseball:

There are some good players on that list! Luis Arraez, like Stanton, has the outlier ballpark to himself. Arraez basically never swings hard. Some other interesting players are at the bottom: Verdugo, Paredes, McNeil, Turner, Turang. These are your batting average guys, but some of them are capable of hitting for decent power.

Statcast can then use bat speed to back a much more useful stat: square-up rate. Physics tells us that there is a maximum expected exit velocity for any given swing speed if you hit the ball perfectly.* If you don’t hit the ball squarely, you will lose some exit velocity. Who are the best hitters in baseball at squaring up the baseball?

*I don’t know if they try to account for different bat weights.

There are a lot of soft swingers on this list. That makes sense: if you swing less hard, you should be able to aim the bat at the ball a little better. Luis Arraez can have a .324 career batting average because he’s one of the best in baseball at hitting the ball on the sweet spot, so it doesn’t hit a lot of weak ground balls or pop ups.

But damn, Juan Soto! Other than William Contreras, he is the only true hard swinger on this list. We often talk about Soto’s superhuman plate discipline in the context of his walk rate. But his talent also manifests in a near-unique talent to swing hard and square up the ball. It’s incredible.

We can see just how great Soto is with a simple scatter plot: bat speed compared with square up rate:

Soto, Arraez and Stanton all sit in alone on this plot, but I’ve highlighted some other interesting players. Judge is in a bit of the square up rate danger zone. I’d be curious to see his 2022-2023 numbers, because my instinct is that when Judge is on he’s closer to where Alvaez or Ohtani are. Alex Verdugo is a bit of a discount Arraez. Mookie Betts is edging toward unicorn as well.

Wait, what the heck is happening with Mookie Betts? The dude hit 39 home runs last year, yet he has a below average swing speed. High square-up rate or not, that doesn’t make sense. He’s in the neighborhood with Nico Hoerner and Brendan Donovan on this plot—not exactly slugger territory.

To answer that question, we need to look at the distribution of a player’s swing. Before we look at Betts, let’s take a look at the distribution of Giancarlo Stanton’s swing speed:

Stanton swings hard, every time. He average speed is about 81 mph. Sometimes it’s a little faster. Sometimes a little slower. But he doesn’t really take much off his swing. The variance in his swing speed is basically random.

Let’s compare Stanton to Anthony Rizzo:

These are very different distributions. Rizzo has about three swings: his choke-up, two strike swing looks a lot like Luis Arraez’s. He has also has a normal swing, which looks a lot like your average major leaguer. Finally, every once in a while he’ll take a power swing, over 75 mph.

That doesn’t make Rizzo a great hitter, but it shows why he manages to put up solid numbers while physically declining. I haven’t checked yet, but I’d expect his square up rate to be much higher on slower swings. He probably took more power swings when he was younger, or maybe his two strike swing was a little faster.

What about Mookie Betts?

That’s a young Rizzo swing if I’ve ever seen one. Betts modulates his swing just like Rizzo. Sometimes he swings slowly for a single, sometimes he reaches back for a power swing. He’s a tick faster than Rizzo on all swings. He also has a Soto-like square up rate. Hall of Famer right there.

I could go on. I probably will soon. These are the first genuinely new data that we’ve had for batters in a long time. Thank you, MLB and Statcast.