On the Ball

September 20, 2019
FULL SWING Jorge Soler of the Kansas City Royals connects for a home run on June 9.
KYLE RIVAS—GETTY IMAGES

Major League Baseball (MLB) has a home-run problem. The number of home runs increased sharply in 2015 and has continued to rise. In 2017, batters hit 6,105 homers, setting a new record. This year’s number will be even higher. Batters have already hit more than 5,500 home runs.

But more homers means fewer balls in play, and for many fans, that means less-exciting games. So what’s going on? Some people wonder if the balls are being made differently so they’ll fly farther. The league says this isn’t happening.

One thing is certain: Something is different about the ball. “We don’t know exactly what yet,” says physicist Alan Nathan. He’s part of a team of 10 experts studying the baseball problem. Nathan doesn’t think the ball was changed on purpose. “Whatever the answer is, it’s something very subtle,” he says.

Spin Matters

The experts set out to solve the mystery by testing baseballs used since 2015. They took some apart and looked inside. They fired others from an air cannon to see how fast the balls flew.

The experts also tested for bounce. The more bounce a ball has, the faster it leaves the bat and the farther it flies. But bounce tests showed consistency between the balls.

Then the experts tested the “drag” of the baseballs. As a ball spins through the air, the air pushes back. This causes drag, which slows down the ball’s spin. That can hold the ball back.

Sure enough, drag had decreased over the years. Baseballs cut through the air more easily. So which feature of the ball has changed to reduce drag? The experts aren’t ready to say.

Variations are bound to happen, Nathan says. Baseballs are handmade. No two are ever the same. MLB could decide to make a change. The ball could be made the way it was before 2015. Should MLB make baseballs more uniform, like golf balls are? “You could do that,” Nathan says. “But then it wouldn’t be a baseball.”

Made to Order

By MLB rules, all game baseballs

  • are made of a core of rubber or cork wrapped in yarn and a horse- or cowhide shell.

  • are 5 to 5¼ ounces and 9 to 9¼ inches around.