This five-part series examines how swing biomechanics and the proliferation of technological tools are helping hitters. Part 1 explored the history of this field and the origin of a few key devices. Part 2 looks at newly emphasized swing traits and how they’re being applied.
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Seattle Mariners outfielder Mitch Haniger was a minor leaguer riding a spring training bus in 2015 when he overheard a conversation with career-altering ramifications. Then in the Diamondbacks organization, he listened in as big leaguers A.J. Pollock and Nick Ahmed discussed hitting in a way that ran contrary to everything that he’d ever been taught. How do I keep the bat in the hitting zone for longer?
Soon afterward, Haniger downloaded an ebook written by independent hitting coach Bobby Tewksbary, Elite Swing Mechanics. The 120-page written tome and supplementary video tutorial, Haniger says, emphasized “facts and physics” in place of baseball truisms such as “stay inside” the ball and “swing down”—imprecise phrases that can mean different things to different players. (A pitched baseball typically reaches the batter while traveling at a downward angle of 7 to 10 degrees, which ought to dispel any notion of swinging down on the ball.)
Stil, Haniger struggled early in Double A that season and saw his playing time wane. He asked to be demoted and went back to Class A ball, where he “changed everything about my swing.” By August of the following season, Haniger had made his major league debut, going 2-for-4 with a double and a triple against the Mets. Traded to Seattle in the offseason, he joined the Mariners and blossomed into an All-Star who received MVP votes in 2018. Much of his mechanical overhaul was done under the guidance of a consortium of gurus: Craig Wallenbock, Doug Latta, Tim Laker, and Matt Lisle. (Laker is now the Mariners’ hitting coach, and Lisle is the White Sox’ hitting analytics instructor.)
The right-handed slugger now quickly whips the bat barrel into the zone, where it remains on a slight upward plane toward the ball. This grants Haniger more time to react to the pitch and adjust his swing. When he does make contact, this swing path is more likely to send the ball on an airborne trajectory, which can maximize damage. To this day, Haniger uses tools such as the Blast Motion bat sensor to track his swing path and the Rapsodo and HitTrax tracking systems for feedback on both his swing path and batted-ball data.
“Five years ago, the swing was still a secret,” Tewksbary says. “Now, it’s not.”
A growing number of major league hitters have rejuvenated their careers by reinventing their swings. Sluggers such as Josh Donaldson, J.D. Martinez, Mookie Betts, Justin Turner, and Daniel Murphy are among the most high-profile players to have improved their fortunes dramatically—either resuscitating careers going nowhere or adding additional power.
But another thing has also become clear: what separates Double A players and big leaguers has less to do with raw athleticism than it does with the finer points of biomechanical sequencing.
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A former first-team All-Ivy League outfielder at Yale, Dave Fortenbaugh left sports research in 2013 to become an engineering consultant who specializes in injury biomechanics. But he spent the better part of five years working at the American Sports Medicine Institute in Alabama, where he collected data on 43 Double-A players who took batting practice in front of eight 3-D motion capture cameras and on two force plates.
And Fortenbaugh’s 2011 dissertation for the University of Miami, aptly named “The Biomechanics of the Baseball Swing,” remains the authoritative work on the subject. Every few months another email rolls in from a father, a coach, a reporter, or an MLB executive wanting to know more. “No matter how far I keep getting away from it,” Fortenbaugh says with a laugh. “I keep getting found.”
Among the Double-A hitters who swung a bat in his lab, Fortenbaugh found that all but one or two had the physical capacity to hit the ball very hard, on par with big leaguers. But the challenge for all of those Double-A players, Fortenbaugh says, “is consistency”—a high hard-hit rate, or what turned the raw version of Mitch Haniger into the refined version of Mitch Haniger.
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The concepts behind mastering such consistency aren’t entirely new. In his 1968 book, The Science of Hitting, Ted Williams wrote about the need for “a slight upswing” while generating power with the hips. And some early biomechanical swing work was conducted in the early 1990s. But the recent widespread adoption of new tools have democratized the ability to collect meaningful data not just in labs but also in batting cages around the country. “I’m learning that some of the best patterns, some of the most optimal patterns that we’re chasing in 2019, were being done way back with Babe Ruth, [Roberto] Clemente, and guys right when baseball started,” says Reds assistant hitting coach Donnie Ecker. Technology, he adds, “helped us clear the fog.”
This advanced understanding of hitting has followed a similar awakening in pitching—and perhaps necessarily so. “When we understood the story of the pitch, we understood the story of the [swing] path,” says Phillies hitting coach John Mallee, who previously held that same job with the Marlins, Astros, and Cubs. “Once we really understood the story of the pitch, we knew how to match the pitch with the path.”
A fastball traveling in excess of 90 mph takes four-tenths of a second to reach the plate—a literal blink of an eye—and the average big-league hitter must decide whether or not to swing at its halfway point. Hitters, says Blast Motion’s director of MLB sales Justin Goltz, have “a lot of style and flair and individual movement patterns. But at least for those last 200 milliseconds, we’re starting to come to some common ground—an understanding of what principles matter—and also measuring those principles so we can do it repeatedly.”
That commonality—the kinematic sequence, or kinetic chain—starts with the ground. Hitters generate force from the bottom up, transferring energy through their legs to the hips, pelvis, trunk, and then arms. Human beings are reciprocal movers, working muscles across our bodies when we do everything from crawling and walking to hitting a baseball. Each part of the chain rotates and then stops to fire the next link.
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As an initial part of this sequencing, coaches at all levels tell hitters to open their hips. But data from K-Motion’s six-sensor vest indicates that pro hitters stop their hips after a 70-degree turn, compared to the average amateur who rotates 90 degrees. “In reality, you don’t need to focus on opening them or making them spin, you need to focus on stopping them,” says Eugene Bleecker, the founder of 108 Performance, a player training facility in southern California. “The sooner you decelerate or stop your hips, the faster you accelerate your trunk.”
That same principle applies to the next sequential stage of hitting. The hips stopping triggers the trunk rotation, which then slows as the arms whip the bat over the plate. (This concept is similar to fly fishing: fishermen throw the rod forward, but it’s the rapid stopping of the rod that transfers the energy to the line and throws the fly out over the water.)
“This idea of everything accelerating to contact is completely false,” says Dr. Greg Rose, the co-founder of golf’s Titleist Performance Institute and baseball’s On Base University who calls the kinematic sequence “the closest measurement of athleticism.”
“The best hitters in the world, they transfer energy from their lower body to their trunk to their arms to the back,” he says. “That summation or addition of energy creates the best of the best. There’s this wave of energy that starts from the ground and works its way up through the body, and I tell people, ‘We can measure that wave of energy.’ ”
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In 2015, MLB’s implementation of Statcast introduced and quickly popularized the terms exit velocity and launch angle as more granular assessments of a swing, as opposed to whether contact resulted in a hit or an out. Those measurements, however, focus on the ball and not the batter. But they ignited curiosity and, because of advanced technology, “opened the door for this new interest in the biomechanics of the batter,” says Glenn Fleisig, the research director of ASMI, whose lab has intensified its research of the swing.
One of the biggest advocates of the K-Motion vest is Jason Ochart, the Phillies’ minor league hitting coordinator and director of hitting at the Seattle-area Driveline Baseball training center. K-Motion data has shown new evidence that the final stage of the kinematic sequence—involving the upper extremities—is more critical to the process than previously thought.
“In hitting, we talk about the engine a lot—the pelvis and torso, which clearly are important—but I’m finding that the best hitters in the world are really good at transferring that energy with their arms and wrists,” Ochart says. “They’re really able to accelerate up through the chain.”
But don’t mistake that final touch as prioritizing bat speed. Ben Hansen, the VP of biomechanics and innovation at Motus Global, says his company’s lab near St. Petersburg, Fla., tracked some 3,000 swings taken by professional ballplayers, including Astros All-Star outfielder George Springer (see embedded video), in a controlled environment using optical tracking and sensor-laden hitters and bats. The researchers and coaches have found that hip rotation energy—including both hip rotation velocity and body segment mass—had one of the strongest correlations to bat speed. Later segments in the swing chain aren’t afforded the chance to generate as much force.
“A batter needs to react,” Hansen says. “They stay more compact and they explode in short bursts.”
Bat speed, Bleecker says, is a different metric than time to make contact. And moving the barrel faster usually means a longer time for the hitter to make contact because of the time it takes to generate that speed outside of the kinematic sequence. An ideal time to contact is quick and efficient—about 120 milliseconds, he says.
“Bat speed is not something that anyone should necessarily focus on,” Bleecker says. “If you look at major league players, their in-game average bat speed is around 70 miles per hour. In the training setting, it’s around 75 to 77.”
C.J. Handron, the CEO of the bat sensor company Diamond Kinetics in Pittsburgh, concurs with this idea, saying the difference between a bat speed of 73 mph and 75 mph, for instance, “isn’t going to fundamentally, radically change who that player is.” Faster bat speed inherently comes at a cost of worse control and consistency—that once indefinable quality that turned Haniger into an All-Star.
“For the most part, once you’ve achieved a certain level of bat speed, you’re good,” says Buddy Clark, the co-founder of Diamond Kinetics. “You can then focus on things like being able to time up every pitch or spread the barrel speed over the zone at the angles that get you where you need to be.”
This follows the reasoning of the Reds’ Ecker, who says, “Force production is not as important as force transmission. . . . You can produce a lot of force, but the task is to transmit that into the baseball.”
“What we’re finding,” Ochart says, “is a lot of hitters possess enough bat speed to perform better than they are. They’re simply striking the ball sub-optimally because of their bat path and their attack angle.”
Translation: you don’t have to swinger harder to maximize exit velocity, you have to swing efficiently.
“Some guys are trying to be metric heroes,” says Joey Cunha, director of hitting at 108 Performance, “and at the end of the day I want them to be hitters.”
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Since 2015, Rays second baseman Brandon Lowe has trained each offseason at the baseball facility operated by the Bledsoe Agency in Tennessee. While hitting in the cages, Lowe will often wear a K-Motion vest to assess his mechanics and he’ll also fire up the Rapsodo hitting tracker to check his results. The three months he works out each winter offer a chance to experiment with bigger changes.
“That’s where I dive a little bit deeper because there are no consequences the next day,” says Lowe, the early frontrunner for American League Rookie of the Year.
Growing up, Mariners rookie outfielder Braden Bishop received the advice to smack ground balls and use his speed to get on base, but major league defenses—especially with infield shifts—are too good, so he has changed his approach to hit more line drives. He paired K-Motion and Blast Motion together and realized his rotational acceleration was subpar, averaging only 10 to 12g of force. He ramped up his core training and tweaked his swing to improve that number to 15g.
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“It gives me a more clear picture of how to up my numbers mechanically without trying to manipulate the bat to get the number up,” Bishop says.
Hitters have made successful major overhauls without advanced tech, of course. It’s a luxury that wasn’t widely available for Red Sox slugger J.D. Martinez when he reinvented himself after the 2013 season. “Mostly video, to change my swing,” Martinez says, declining to divulge any other methods or tools he uses in order to protect his tradecraft. “We didn’t have the sensors and all that when I was making the change.”
Most hitters rely less on the technology during the season because it’s “not all that useful unless you’re trying to make some sort of swing adjustment,” says Twins catcher Jason Castro. Instead, players shift their focus from process to results. Batted-ball trackers become more important to make sure the ball is being struck as well as possible, especially during indoor cage work. HitTrax and Rapsodo track exit velo and launch angle, thus providing more context than just a vague “good job” as the netting swallows the ball.
“Especially in the cage, guys really like to see their batted ball data,” says Phillies assistant hitting coordinator Russ Steinhorn. “Having those technologies gives them the feedback [more than] just the ball hitting the net.”
Those devices can also help players understand their hot zones at the plate. “The reason I use it is mostly just to show them where they hit the ball the hardest, what areas in the zone, and also what launch angle are they practicing,” says Blue Jays hitting coach Guillermo Martinez.
While some swing metrics still seem a bit too wonky to players—pelvis rotation speed and vertical bat angle, among others—exit velocity and launch angle are more intuitive and commonplace. “You can see instantly, when you talk about the numbers that you’re looking for and relate it to the ball flight, that it kind of sinks in,” the Mariners’ Laker says. “Guys get it.”
Hitting technology is more apt to make a difference in the lower levels of the minors as a player development tool, meaning devices such as Blast Motion are helpful for creating a baseline and periodically checking consistency. But, says Astros general manager Jeff Luhnow, “We’re still in the early stages of figuring out what flaws can be corrected and what can’t.”
But that won’t stop player development groups everywhere from deploying bat sensors, wearable tech, ball trackers, and high-speed cameras.
“A lot of people are gaining a lot of value out of being able to evaluate swings,” says Reds star first baseman Joey Votto. “A little less ‘eye test’ and a little more data goes a long way.”
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