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OC Register: Hoornstra: Baseball motion-capture data could spur a new frontier of injury prevention

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Imagine a three-dimensional graphic of a skeleton pitching a baseball. To the untrained eye, it’s a fantastic curiosity, an 11-year-old’s idea of the perfect Halloween get-up.

To the trained eye, the pitching skeleton is something much more important. It’s the next frontier of injury prevention in baseball.

Motion-capture technology has emerged as a dominant training tool for both hitters and pitchers. By analyzing every movement they use to generate force, hitters and pitchers can try to optimize their individual mechanics in pursuit of the Maslowian ideal of a baseball player: to be the best version of one’s self.

This is essentially why so many Dodgers and Angels players – Shohei Ohtani and Mookie Betts, among others – have spent parts of their recent offseasons at the Driveline Baseball facility in Kent, Washington. Driveline uses motion-capture analysis among its many digital training tools. Its social media feeds are littered with the baseball-playing skeletons – the graphical outputs of motion-capture markers – to prove it.

One skeleton can be mesmerizing. Two make for interesting side-by-side comparisons. Three or more quickly become a robust data set. And that’s where the injury prevention piece comes in.

“We do have, in my opinion, the most robust longitudinal pitching and hitting motion-capture data sets in the world,” said Kyle Wasserberger, Driveline’s principal sports scientist and coordinator of health and performance research.

Last December, Wasserberger sounded a call to action: Driveline would be releasing its motion-capture data to the public for research purposes. It’s been live on GitHub ever since.

Wasserberger and colleague Alex Caravan presented their preliminary motion-capture research into one understudied topic at the annual SABR Analytics convention in March. They were interested in learning more about how pitchers create deception. More specifically, what can pitchers do to fool a hitter into thinking the ball is going someplace it isn’t? How do some pitchers inadvertently tip hitters off to what pitch they’re about to throw?

“We tried to look at the beginning of the motion, thinking if hitters are picking something up it’s probably early, before the pitcher strides down the mound, rather than after,” Wasserberger said.

Their research examined just the initial movement of pitchers’ skeletons – not the movement of the baseball, not the way the ball was gripped – to see if they could predict what kind of pitch was being thrown. Remarkably, they could.

So, how do the best pitchers in the world avoid tipping their pitches just by the manner in which they begin their delivery? The answer is one of many potentially lying in the public motion-capture data.

Deception is another layer to add to the science of pitching, one that has already produced an explosion of knowledge about how pitchers generate speed and movement – and contributed to a historic rise in strikeouts across Major League Baseball.

These kinds of rabbit holes can be a fascinating intellectual pursuit. They’re also the source material that the anti-analytics crowd loves to seize upon with derision. Commissioner Rob Manfred recently told a story at an executive luncheon in New York, reported by The Athletic, about a conversation he had with a team owner.

“I am absolutely convinced that analytics is an arms race to nowhere,” the owner reportedly told Manfred. The commissioner responded, “it’s become one of my favorite lines because I think it’s actually true.”

According to the report, Manfred went on to say that analytics did “damage” to the game.

The timing of the remark is important. MLB introduced three new rules prior to this season, some of which were designed to essentially undo the effects of advanced quantitative analysis in baseball. Whether you believe trends like defensive shifts and fewer stolen base attempts “damage” the game or not, Manfred is unequivocally trying to undo them.

The same analytical tools that allowed pitchers to add velocity, and design breaking balls that bend from the middle of the plate to roughly the on-deck circle, ultimately helped increase the frequency of strikeouts. This in turn put off fans who would prefer a game with more balls in play. Analytical tools that help pitchers increase their deception skills would only further this trend.

But to use this argument as evidence that analytics “damage” the game is to throw the baby out with the bathwater. The initial research on deception amounts to low-hanging fruit in the overall body of knowledge that Driveline’s motion-capture data might unlock.

The big prize is injury prevention. Currently, teams can – and do – pursue competitive advantages in injury prevention by expanding their own biomechanical modeling capabilities. How does that advantage trickle down to the fan?

Maybe a team will trade a player who it deems likely to suffer an injury or choose not to tender that player a contract in free agency (see Correa, Carlos). Other times that means a team will work to improve a player’s mechanics behind the scenes, or privately decide whose workloads ought to be limited to reduce their chance of injury.

The upshot to the team who holds these advantages, in theory, is a relatively healthy roster. The upshot to the baseball-consuming public is minimal, as teams whose biomechanical models are less predictive run the risk of fielding a more injury-prone team.

If every team could act on the best insights into injury prevention, the best baseball players in the world could plausibly spend more time on the field – a win-win for fans and players. The only “losers” would be the teams that currently hold a competitive advantage in injury prevention. So, how might every team access those insights?

“We’re in a unique position to fill that gap in the current research world,” Wasserberger said. “You cannot find a peer-reviewed study that has a sample of 30 pitchers that all threw 90 mph, but you can in our data set. That’s what we want to do at Driveline, is publish these normative values, these descriptive papers that scientifically examine the hitting and pitching motions in the elite players that are out there.”

To be clear, this is not a short-term goal. It’s a long-term pursuit made possible because of advances in quantitative analysis, technology, and Driveline’s ever-expanding data set of major league players. Damage is done to baseball when these tools are left unused. If they were available 60 years ago, could they have prolonged Sandy Koufax’s career? Can they save the elbow of the next Koufax?

The answers, hopefully, lie in the skeletons.

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1 hour ago, Rollinghard said:

There is a guy who predicts which pitchers are going to need Tommy John based off their position as stride foot touches ground. If at that point the pitchers arms are in the upside down W position they are going to be injured. 


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