MLB's new bat speed numbers: The good, the bad and the uncertain future (2024)

Track it. Vet it. Scout it. Get it. That’s been the playbook when it comes to new publicly tracked statistics in the past — they’ve moved from fancy new numbers to accepted metrics and then scouting and player development goals over time. Now that MLB’s Baseball Savant website has unveiled a new suite of bat tracking numbers including, among others, bat speed and swing length, we are left to wonder whether the past will repeat itself.

In 2006, PITCHf/x systems were installed in every park and pitch velocity was tracked publicly for every pitcher. Since then, the average four-seam velocity in the league has gone up 2.8 mph (along with associated injuries).

In 2015, baseball moved to TrackMan’s radar-based systems in every park, and spin rate was observed (instead of calculated) for every pitcher. Since then, spin rate has gone up, albeit with some bumps and bruises (and perhaps associated injuries).

In 2020, MLB’s parks went back to optical player and ball tracking by adding Hawk-Eye cameras. Since then, exit velocities and launch angles have gone up. More on injuries later.

Now baseball is giving us bat speed as measured at the sweet spot, about 6 inches from the head of the bat, and at contact, or closest point to contact for a miss. There is a handy chart to explain some of the newest statistics, how they are measured, and what they can tell us.

Vetting these new statistics is more complicated, and will take place over the next few years as we add more data to what’s currently only available for this season. But that process has been underway across baseball already, and we can tell that bat speed is important, especially for power.

“Bat speed affects exit velocity,” physicist Alan Nathan said. “For a squared-up impact at the sweet spot, each mph additional of bat speed increases exit velocity by about 1.2 mph. For a ball hit at the optimum launch angle of 25-30 degrees and around 100 mph, the corresponding increase in fly-ball distance is about 6 feet.”

Six feet is the difference between the warning track fly ball and a home run. STATS Perform estimated that, if we removed 6 feet from every home run last year, there would have been 365 fewer homers. Even if we look at this year’s small-sample outputs, you can see how bat speed correlates with power.

Hitters are aware of this relationship.

“It’s absolutely important,” Oakland Athletics designated hitter Brent Rooker said. “In a vacuum, all else the same, swinging faster is never going to be a bad thing. Just like throwing harder is going to be better.”

“Bat speed is a foundational speed that you need to have,” St. Louis Cardinals outfielder Lars Nootbaar said.

“Yes, absolutely bat speed is important,” Boston Red Sox director of hitting Jason Ochart said. “To suggest otherwise is crazy.”

Not every coach feels the same way.

“It seems absurd really to even argue that training to move the bat faster could ever be a bad thing, but the caveat in our game is that it involves a complex task with precision, skill and timing,” Pittsburgh Pirates hitting coach Andy Haines said. “It’s not slow-pitch softball.”

“Most of the best power hitters in MLB don’t have the best bat speed, it’s more about how you get the bat up to speed, when and where,” Eugene Bleecker of 108 Performance said.

“If bat speed alone was an absolute measure of success, then the top bat speeds would all be the top hitters in baseball,” Doug Latta of The Ball Yard said.

To be fair, you can look at that chart and see the positive relationship and ascribe the spread around that trend line as noise. Or you can see that noise as complications, reasons that bat speed is not worth pursuing as a singular training or scouting goal.

If you play around with the Baseball Savant visualization tool, you’ll quickly see that bat speed has a positive correlation with whiff rate and a negative correlation with square-up percentage, meaning as bat speed goes up, whiffs and mis-hits go up. And that’s a problem for hitters and coaches because you have to make contact and make it flush to hit for power in the big leagues, too.

“Sweet-spot accuracy is the No. 1 thing, even if bat speed is really important,” New York Mets slugger Pete Alonso said. “You have to hit the ball over 100 (mph) for it to go, but that takes accuracy and bat speed.”

“You’ve had great prospects with elite bat speed, not to put anyone under the bus, but Clint Frazier had elite bat speed,” A’s hitter J.D. Davis said. “It’s more complicated than that.”

Yes, bat speed is king. But what happens when hitters face better stuff? I built a series of models across various levels of Stuff+ and plotted the effects of bat speed, bat to ball, and swing decisions on run value. The results show that bat speed matters less as stuff improves pic.twitter.com/3sGLbBurpa

— Connor Curtiss (@connor_curtiss) August 21, 2023

There’s evidence that contact ability becomes more important against the nastiest of pitchers, so hitters and teams might not want to make even more of a power/contact trade-off than they’ve made so far.

But there’s a flaw in this type of analysis, too. We’re looking at individual players in the big leagues, so there’s a selection bias at play. We’re only looking at a select group of players, not all baseball players.

“The hitters who can get away with whiffing and still make it to the big leagues have bat speed and do damage,” Ochart said. “The low bat speed hitters in the big leagues are able to survive because they put way more balls in play. The best hitters usually do both.”

“If a player has bad bat speed and makes bad swing decisions, they’re not in the major leagues,” Nootbaar said.

If we look at bat speed by level, it’s pretty obvious how important bat speed is to advancing to the professional ranks. According to Dan Aucoin, the assistant director of foundational research with the Philadelphia Phillies, the average bat speed in high school is around 65 mph. In college, it’s around 68 mph, and in the minors, it’s just above 70 mph. We know from directly tracked bat speed that the average in the pros is 72 mph.

It’s still kind of important how a hitter gets to that bat speed.

“There are some diminishing returns if you sell out for bat speed and lose barrel control or awareness of the strike zone or lose the ability to make contact,” Rooker said. “If you’re making your swing mechanics worse or your timing worse, that could be a problem. There’s a shorter timing window.”

That’s borne out in the numbers. Take a look at how the top left of this chart is deep blue (poor production) and how the bottom right is lighter (good production).

A short, fast swing is the goal (those are the white dots). If you want to see it in table form, here are the major-league hitters who have 74 mph-plus bat speed and shorter than a 7 1/2-foot swing.

“Efficiency in the swing is everything,” Bleecker said, and this list underlines that point.

“How far is your bat traveling? Is it back and around?” Latta said. “We talk about being direct. We talk about a direct swing.”

“I’ve personally gotten guys past certain thresholds and made them worse in-game,” Texas Rangers director of hitting Donnie Ecker said about the quest for bat speed. “Where in the body are we moving the needle, and how does the value-add in speed interact with the overall movement system? The higher you go up you will find preferred ranges where guys are at their best as hitters. We don’t have to guess on that anymore.”

Keeping player development and training environments more game-like has been a huge emphasis recently in player development, and you can see why. Just adding bat speed by making the swing longer isn’t a great idea, and the game will show you if that’s what you’ve done.

“If you’re adding speed in game-like environments it’s hard to take long s—ty disconnected swings that don’t translate,” Driveline director of hitting Tanner Stokey said. “If you’re training bat speed off of tee/front toss or even worse (in terms of transferability) dry swings, there’s a much higher likelihood swings will get longer and more disconnected because it’s easier to get away with that in controlled environments.”

“Hitting the ball 100-plus off the tee is irrelevant,” Latta agreed. “It’s hard to make a game-like environment, other than maybe live at-bats, and even then, the psychology is that you’re facing your own guy, and you don’t have the adrenaline of competition.”

Still, bat speed has its proponents who say that with the right training in the right environments, it’s possible to train a short swing with good timing that is also fast.

“The skills of making contact and swinging fast are themselves not correlated in a sense that having or increasing one will decrease the other,” Ochart said, and a lot of players end up agreeing if adding the “in a vacuum” qualifier. “Most times being faster means being quicker, too.”

The consensus building is happening. It’s happening right now, as some teams have coordinated weighted bat programs in the minor leagues. Bat speed most tightly correlates with maximum exit velocity, so teams can use that more available number to scout for their next hitters. Major leaguers like Ramón Laureano are buying weighted bats and doing training on their own. The Los Angeles Dodgers sent their hitters for a round of bat speed training. This is happening … much in the same way that the league once started training for pitch velocity.

Are there going to be similar ramifications?

Maybe. Triston Casas, who has bat speed just outside the top 10 percent in the league, recently hurt his rib cartilage by turning so fast. He had some very eye-opening things to say.

“(The doctor) pretty much chalked it up to me being so big, rotating so fast, so many times that I created a car crash within my body,” Casas said. “It was a matter of time before this happened. He said it was something similar to like a pitcher needing Tommy John, just an inevitable thing that was going to happen sooner or later.”

Wow. This isn’t just a one-off thing, either. Thanks to Derek Rhoads at Baseball Prospectus, we can see that there’s a bit of a trend emerging with rib and oblique injuries in hitters.

This might have to do with the mechanics of chasing bat speed. The obliques might fail because the body is having a hard time decelerating from its top speed as it turns.

“When we move athletically and naturally, deceleration is built in,” Latta said. “If the front shoulder moves off, you lose that natural decel.”

“We’ve noticed a strong correlation with some movement pattern red flags of the lower half and how the body handles that force up and the chain,” the Pirates’ Haines said. “That leads to not only oblique but lead arm shoulder injuries as well.”

How that deceleration is trained — some places use water bags, others emphasize mechanics — is important and a big matter of debate. It’s hugely important as bats will probably begin to move faster over time if the past is prologue. But pitchers and hitters might also benefit from an even simpler approach: tracking their workloads. Just as a pitcher throws bullpens and has to track how often he puts in game-like effort in a training environment, the hitter should do the same to avoid fatigue and injury.

“Yeah, we swing a ton,” said Oakland’s Zack Gelof, who is on the injured list for an oblique injury. “They track workload like how much we run and stuff in the weight room but not swings.”

Less might be more for batters trying to grind their way to bat speed and success in the major leagues, too. Especially on game day.

“We shut people down,” Latta said. “I tell them we’ve got some time, but we have to get the point across and do this work in the cage in a short time frame, because once your body is tired, you start compensating.”

“Overall, something Dustin Lind and I got into when in San Francisco together, was thinking of our ramp-ups through the lens of a physical therapist,” the Rangers’ Ecker said. “Could we get the central nervous system to only ramp up twice before a game? We felt like that, as simple as it sounds, was a massive win in a space that’s used to guys swinging 350 times before a game. There’s a reason pitchers don’t throw four bullpens before they start that night.”

Some teams are using wearable tech to monitor hitters’ fatigue as well as pitchers’, and that’s going to be more important. Because, as these stats become more accepted in the public space and hitters and coaches see the correlations between bat speed and power, and hitters begin to train for bat speed specifically, these injuries might become even more commonplace.

We can learn from the past, and do our best to mitigate the effects we’ve seen before from similar enterprises, but we might not be able to escape it as hitters chase bat speed.

“There’s a maximum the human body can handle, and we’re pushing up on it,” Rooker said. “Long enough timeline, the body adapts and evolution takes place, but as far as what it can handle right now, we’re reaching the top end of it.”

(Photo of Triston Casas: Lindsey Wasson / Associated Press)