Biomechanical analysis is baseball's newest trend.

The stadium scene.
April 24 2007 11:24 AM

Move Over, Moneyball

Stat nerds are out! Biomechanics nerds are in!

Daisuke Matsuzaka. Click image to expand.
Daisuke Matsuzaka of the Boston Red Sox

The other day I was talking baseball with a friend. At first we were, lamely, comparing our fantasy teams. This is something I never really enjoy. How much can be said about how eye-popping A-Rod's stats are or how badly some guy in your league got fleeced in a trade?

Seth Stevenson Seth Stevenson

Seth Stevenson is a frequent contributor to Slate. He is the author of Grounded: A Down to Earth Journey Around the World.

After a while, though, we drifted into a more interesting conversation. In the midst of marveling at Manny Ramirez's hitting genius, my friend suddenly got out of his chair and mimicked Manny's swing. "He keeps his weight back," my friend said, lifting his knee and cocking his elbow, "so he has unbelievable balance right into his follow-through." Here my friend swung his arms and watched an imaginary home run sail into the distance. Now I hopped up, too, holding my own invisible bat. Soon we were discussing hip rotation, and forearm pronation, and how to keep your head quiet through the swing.

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To you, this may seem no less (and perhaps even more) lame than gabbing about fantasy stats. But to me, this sort of physiological analysis is a more engaging way to look at the game than just reading lists of numbers. And I'm not alone: There's been an explosion of interest lately in "mechanics"—the elemental physical movements that go into an athletic skill. Suddenly, regular fans are concerning themselves not just with a pitcher's ERA, but also with the length of his front foot stride, how far he opens his shoulder, and the location of his release point.

This post, from a Red Sox message board, dissects the pitching motion of Daisuke Matsuzaka:

[H]is mechanics are all over the place. … [H]e gets into these spells where he really flies open, he doesn't stay balanced and he gets bad recoil on his arm motion.

This post is about pitching prospect Craig Hansen (and remember, this message board is for fans of the team—not physical trainers or sports medicine specialists):

I'm not necessarily a proponent of the inverted W. I'd much rather have a horizontal scap load (horizontal W) than the inverted W. … [A]t max scap load, I like the ball to be either level or below the elbow and shoulder line.

I feel exactly the same way about scap loads.

Mostly, I'm interested in this type of analysis because it seems like a way to better myself as a fan—a way to get deeper insight into what's really happening down there on the field, moment by moment. I like to ponder the alchemy of anatomy and coordination that allowed Pedro Martinez, who is about my size—I once stood next to him in the Red Sox locker room—to throw a baseball at 97 miles per hour. I like to study players in the midst of slumps to see if I might diagnose their ills. (Nomar Garciaparra, for instance, starts slumping when he's pulling his head and front shoulder off the ball and falling to his left.)

Of course, fans have always done this sort of thing. We've observed the distinctive pitching motions of players from Luis Tiant to Dontrelle Willis. Little Leaguers imitate the signature batting stances of star hitters. The difference now is: 1) The Web has created a viable platform for writers who do nothing but detailed biomechanical analysis, and 2) super-slo-mo videos on YouTube let everybody get in on the act. (It's not just baseball, either. There's a thriving community of tennis geeks—OK, I'm one of them—who will watch clips of Roger Federer's one-handed backhand for hours on end. The way he keeps his eyes locked on the ball, the way his forearm supinates to impart a topspin rotation … aaaahhh.)

You could view the mechanics obsession as just another evolution in fan identity. We've always been armchair managers, second-guessing our team's decisions to bunt, or hit and run, or leave a pitcher out on the mound (damn you, Grady Little). Since the advent of fantasy baseball, we've identified more closely with the GMs—analyzing stats, weighing different roster constructions, and calculating salary-to-production ratios. Now, with the mechanics movement, we're all amateur scouts.