MLB Study Links Record HR Spike to Baseball Seams, Launch Angle, Not Juiced Ball

Tim Daniels@TimDanielsBRFeatured ColumnistDecember 11, 2019

HOUSTON, TX - OCTOBER 30:  A bag of baseballs is seen on the field before Game Seven of the 2019 World Series between the Houston Astros and the Washington Nationals at Minute Maid Park on October 30, 2019 in Houston, Texas.  (Photo by Tim Warner/Getty Images)
Tim Warner/Getty Images

A study commissioned by Major League Baseball concluded the record 6,776 home runs hit during the 2019 season were a result of "inconsistent seam height" on baseballs and "changes in player behavior" related to launch angles—and not a concerted effort by MLB or manufacturer Rawlings to "juice" the ball.

ESPN's Jeff Passan provided details from the initial findings of four professors—Drs. Alan Nathan, Jim Albert, Peko Hosoi and Lloyd Smith—who wrote "no evidence was found that changes in baseball performance were due to anything intentional on the part of Rawlings or MLB and were likely due to manufacturing variability."

The study determined the average seam height decreased about five-thousands of an inch based on a review of balls used in 2019 compared to those from the range of 2013-15, but the professors were more concerned about the lack of consistency, with balls ranging from .025-inch to .0425-inch seams, per Passan.

MLB requested the review after several pitchers spoke out about the baseballs during the season.

None discussed the issue more strongly than Houston Astros starter Justin Verlander, who overcame what he described as a "100 percent" juiced ball to win the 2019 AL Cy Young Award.

He told reporters at the All-Star Game he believed commissioner Rob Manfred was at the center of the change:

"It's a f---ing joke. Major League Baseball's turning this game into a joke. They own Rawlings, and you've got Manfred up here saying it might be the way they center the pill. They own the f--king 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."

The issue also reached the minor leagues as hitters at the Triple-A level enjoyed a massive increase in homers last season after it switched to using the same style of ball as MLB:

Minor League Stories @MinorsTeamNames

Final AAA Home Run Totals: 2018 - 3,652 2019 - 5,749 AAA games switched to MLB baseballs in 2019.

Meanwhile, clubs that qualified for the playoffs felt the balls changed for the postseason. St. Louis Cardinals manager Mike Shildt said their analytics department found a "four-and-a-half foot difference" of less travel, while Robert Arthur of Baseball Prospectus determined there was increased "drag."

The study looked into those claims but determined "the sample size was far too small to control for players in any meaningful way," and the playoff baseballs it looked at were similar to the regular season, per Passan.

A "more detailed report" about the findings will be released by the professor group at a future date.