Stephen Haas/The News-Gazette Alan Nathan, emeritus professor of physics at the University of Illinois, poses for a photo in the News-Gazette studio Tuesday, May 29, 2018, in downtown Champaign. Nathan helped lead a group of scientists to investigate the increased number of home runs in the 2015-2017 seasons for Major League Baseball.

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If he told you, he would have to kill you.

So Alan Nathan, the University of Illinois scholar who is the unofficial physicist of Major League Baseball, is keeping his lips sealed.

“There is a limit to what I can talk about,” said Nathan. “It will become public soon.”

What is so sensitive that discretion is required?

Nathan and a group of fellow academics, on assignment from MLB Commissioner Rod Manfred, are closing in on the cause of the home runs being hit out of MLB stadiums in record numbers.

A previous study released in 2018 focused on a change in the baseball’s aerodynamics that are allowing them to be hit longer distances. That study could not identify what exactly was different in terms of aerodynamics.

But that was then, and this is now.

“We believe we know what property of the ball has changed on average that would change the aerodynamics,” said Nathan, who indicated additional tests are being done to confirm the theory.

The 2017 study cited the dramatic increase in home runs. In 2008, 3.6 percent of batted balls ended up in the bleachers. By 2017, the percentage increased to 4.8 percent — an increase of one-third in 10 years.

Last year, the number of home runs fell, but the numbers are up again in 2019 — 3,961 home runs in the first half of the year.

That increase and the conspiracy theory behind it have been driving conversations in the world of professional baseball. The talk hasn’t all been at a scholarly level.

Earlier this month, Houston Astros pitcher Justin Verlander, who at that point in the season had given up a league-high 26 gopher balls, delivered an obscenity-laden screed that alleged a conspiracy led by Commissioner Manfred.

Referring to MLB’s purchase of baseball manufacturer Rawlings, Verlander complained that “they own the company.”

“If any other $40 billion company bought out a $400 million company and the product changed dramatically, it’s not a guess as to what happened. We all know what happened. Manfred the first time he came in, what’d he say? He said we want more offense. All of a sudden, he comes in, the balls are juiced? It’s not coincidence. We’re not idiots,” he said.

MLB pitchers also are not physicists, statisticians, mathematicians or engineers. But they have a feel for the ball laymen do not.

So Verlander, an All-Star, is on to something, although whether any changes in the ball are intentional remains to be determined.

In their first study two years ago, Nathan and his colleagues, including those at Washington State University’s Sport Sciences Laboratory, focused on three possible causes for the increase in home runs.

They were:

— livelier balls.

— batter behavior.

— aerodynamics.

They found little evidence to support the first two suspected causes. But they determined baseballs manufactured at a Rawlings plant in a South American country had “better carry" because there is a “reduced drag on the baseball.”

At that time, they eliminated weather as well as size, weight and seam height of the ball as the cause of the reduced drag that allows balls to be hit farther. Nathan, a native of Maine and a Red Sox fan, noted that even slight aerodynamic changes can allow balls to go another 10 or 15 feet. Sometimes that’s the difference between a home run and an easy putout.

Speculation about “juiced balls” in MLB has come and gone over the years. It generally produced an “is too, is not” debate because it was impossible to subject the theory to scientific scrutiny.

But Nathan said “better measurement techniques” that are at the heart of baseball’s sabermetrics revolution laid the groundwork for answering the question.

“It’s the new technology that is giving us much more information,” he said.

For example, since 2015, all Major League stadiums have StatCast systems that analyze on-field baseball and player movements in an automated manner that is high in both speed and accuracy.

As a result, new phrases like “exit velocity” and “launch angle” have become part of the game. “Exit velocity” refers to the speed of the ball after it is struck by a bat. “Launch angle,” which is critical for home runs, refers to the degree of height in which a ball is hit. After all, few line drives leave a ballpark while many high flies do.

IF Nathan and his colleagues are able to properly identify what’s enhancing the ball’s aerodynamics, that raises another issue. Is it a problem, and what, if anything, will MLB do about it?

“That’s a much more difficult question to answer,” said Nathan.

Jim Dey, a member of The News-Gazette staff, can be reached by email at or by phone at 217-351-5369.


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Jim Dey is a staff writer for The News-Gazette. His email is