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


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.


Consider the Concrete Donut

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Ben Schulman wrote a long, interesting article about stadium architecture over at The Hardball Times today. He asks us to consider the old concrete donut stadiums — multipurpose parks like Three Rivers and The Vet — and to think about what we have gained by their near-extinction. And what we’ve lost.

The article starts out with what I feared would be too much misplaced nostalgia for the Brutalist, functional places that no longer exist outside of Oakland, with the now de rigueur references to astroturf and weird 1970s baseball. It backs away from that early on, though, and presents what I feel is a thoughtful look at the various approaches to building a ballpark. Stadium geeks and architecture geeks will find much to love here.

From a personal perspective, I have a love/hate relationship with newer parks. I spent a good deal of time going to places like Riverfront Stadium when I was a kid and do not miss them at all. But I also think there have been a lot of missteps in the last 25 years or so too.

Most new parks are pleasant and comfortable places to take in a ballgame, but so many of them are totally unimaginative and uninspiring from an architectural point of view. I am not fan of nostalgia, and so many of them — particularly the ones built in the 90s — were fueled by a great deal of misguided retro-ism that looks backwards. I suspect this is the case because either (a) no one had the guts or vision to look forward; and/or (b) they felt they could make easier bucks by catering to people who think everything went to hell once Eisenhower left office than by doing something bold. To be fair, there are examples of newer parks that eschew the faux old-timey vibe to greater degrees — Target Field in Minneapolis and Marlins Park in Miami come to mind — and I tend to prefer those to more backward-looking places. Again, architecturally speaking.

I think the sweet spot — and the linked article touches on this a bit — are ballparks which think bigger than the bland and dreary functionalism of the 1960s and 70s but which eschew derivative, traditionalist approaches. Parks which were built with then-modern sensibilities and saw their vision through without compromise. Dodger Stadium is a fine, modernist example of this. So too is Kauffman Stadium in Kansas City, about which I wrote a few years ago. They had a great opportunity to do this in Chicago in the late 80s but muffed it. I think Marlins Park could fall into that category if (a) there is ever anything approaching memorable baseball there; and (b) if they stop being afraid of its bold aspects and stop trying to turn it into a vanilla monument to its vanilla owner. The common denominator, I suppose, is that these parks weren’t and aren’t trying to cater to the childhoods of local fans.

Anyway, good read on a slow news day.