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A second study confirms that home runs are up due to a change in the baseball

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Two weeks ago Ben Lindbergh and Mitchel Lichtman released their study at The Ringer which convincingly argues that changes in the composition and construction of the baseball is responsible for the dramatic spike in home runs we’ve seen since the middle of the 2015 season. Yesterday their work was corroborated.

Rob Arthur of FiveThirtyEight, who had last year conducted a study with Lindbergh which proved inconclusive on the matter, has revisited the baseballs as well. Specifically, he used baseball’s data with respect the speed of the ball when it is released from a pitcher’s hand and when it crosses the plate and, based on the loss in velocity in that short period, calculated the ball’s drag coefficient. From that he could compare the drag on the ball from before mid-2015 and the drag since mid-2015.

His conclusion: there has been a significant decrease in the drag on baseballs over the past two years and that decreased drag can account for about five feet of carry on a given fly ball. That, in turn, would account for a 10-15% spike in home runs on average, and a bigger spike in any given month depending on other factors. Arthur:

It’s highly unlikely that we’d see that kind of difference by chance without a real change to the ball: The monthly variation in estimated drag coefficients in the past five seasons varied from around 0.34 to 0.355, a far wider range than we’d expect from random variance alone. In total, the practical effect of shifting from a high-drag month to a low-drag month could be around a 30 percent difference in home run rates.

Arthur cautions us not to become conspiracy theorists here. The change in the ball need not be nefarious as even small alterations in the manufacturing process could lead to these changes. At the same time, he reminds us, that we should ignore MLB’s statements that the balls still fall under the league’s manufacturing requirements and performance parameters, because those parameters are quite broad and allow for these significant variations in ball flight. Even if no one is intentionally doing this and even if the balls are officially up to snuff, they can nonetheless have changed significantly and are the likely culprit for the dramatic home run spike.

Stepping back from the research, this makes a lot of sense. As we’ve noted in the past, there is a long and rich history of changes — even slight changes — to baseball composition leading to dramatic increases and decreases in offensive levels. The dead ball era ended, in large part, because different wool was used beginning in 1919. The National League changed balls in order to intentionally boost offense in 1930 and it worked almost too well. There was a change of baseball manufacturers in the late 1970s which led to a mini spike. 1987 was the year of the so-called “rabbit ball.” That was never fully explained, but there are strong suspicions that Major League Baseball messed with the ball that year.

Other factors matter — new parks with shorter porches, batters making a point to swing with an uppercut, diluted pitching, PEDs, etc. — but none are as significant as changes to the ball itself and none account for the almost immediate spike in homers in the middle of the 2015 season.

Anyway, enjoy the dingers. They’re here to stay. Or at least until the baseballs change again.

 

Nick Williams has been trying to sell Jake Arrieta on the Phillies

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CSN Philly’s Jim Salisbury reports that Phillies outfielder Nick Williams has been working out daily with free agent starter Jake Arrieta in Austin. The right-hander, who won the 2015 National League Cy Young Award, still remains teamless with spring training less than a month away. Williams has been trying to sell Arrieta on joining the Phillies.

Williams said of Arrieta, “He loves it here [Austin]. He has told me he likes working with young guys. I’m like, ‘All right, come on up.’ But I’m not writing the check. I don’t know what he wants. I don’t really dig into that because I’m not really in his position.”

On GM Matt Klentak’s hunt for pitching help, new manager Gabe Kapler said, “The pursuit is very real. I have a lot of trust that we’ll either go in [to spring training] with a new toy or we will pass on the opportunity because we’re better off giving this collection of pitchers a really healthy look because we thought that we could go acquire that piece a little bit later on this season or in the offseason next year.”

Arrieta, who turns 32 years old in March, went 14-10 with a 3.53 ERA and a 163/55 K/BB ratio in 168 1/3 innings last season with the Cubs. The Cubs, Cardinals, and Brewers have been linked to Arrieta this month.

Presently, the Phillies’ starting rotation figures to include Aaron Nola, Jerad Eickhoff, and Vince Velasquez along with some combination of Nick Pivetta, Ben Lively, Zach Eflin, Mark Leiter, and Jake Thompson. Arrieta would certainly amount to a big upgrade in the starting rotation and could make the Phillies a more attractive landing spot for Bryce Harper or Manny Machado, who become free agents after the 2018 campaign. The Phillies are expected to be in the mix for either or both players.