Aroldis Chapman

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MLB: Ball-to-ball variation is more extreme than year-to-year variation

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SAN DIEGO — A press conference was held this morning in the wake of MLB’s report about juiced baseballs. Most of it involved a reiteration of the scientific report. The findings, again: “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.”

I took at least some issue on that finding in this morning’s post based on some non-MLB research conducted by other scientists, but we’ll leave that for another time when those other scientists react to this and conduct additional research of their own. For now I want to focus on something in the report — and confirmed in the press conference — that may be far more notable for baseball fans and baseball players.

In the report, the scientists hired by MLB concluded the following:

  • “In any given year, the ball-to-ball variation in [drag] is much larger than the relatively small change in the mean [drag] that accounts for the change in the home run rates between seasons;” and
  • “Neither the year-to-year changes nor the significant ball-to-ball variation in [drag] could be associated with any specific physical property of the ball, such as seam height, surface roughness, size, etc. Nor could these factors be explained by any changes in the manufacturing materials or processes.”

Translation: if you think the difference between the ball in 2019 vs., say, 2014 is big, it’s nowhere near as big as the ball Justin Verlander may throw to Gary Sánchez in the first inning vs. the one Aroldis Chapman may throw to Alex Bregman in the ninth, and we have no idea why or what to do about it.

The lead scientist on the project, Alan Nathan, and MLB executive Morgan Sword, who is the league’s guy spearheading the whole juiced ball investigation, were asked about that a few minutes ago. Here is the relevant exchange. The first question here was asked by Jayson Stark of The Athletic. The second question was asked by Hannah Keyser of Yahoo Sports:

 

Q. When you speak to people in front offices about the baseball, the most common reaction they have is we’d just like to know going into next season what kind of baseball we’re going to have. Based on this study, do you have any ability to assure them heading into next season whether the baseball is going to behave like this year’s baseball or something else?

MORGAN SWORD: We have some ability, yeah, and I think that one thing that happens in the production of baseballs is that there’s a natural lag between when they’re produced and when they’re used in games, which gives us an opportunity to do some of these new aerodynamic tests that Lloyd has developed prior to the use in games, but to me, one of their most important findings in the prior report and in this report is that the ball-to-ball variability far exceeds the year-over-year variability. So just any given ball can have drag properties that are significantly different than any other ball. [emphasis added]

So in terms of the way clubs prepare for the ball in a certain year, we can give them some information, but I don’t think we’ll ever get to the point where they can have complete certainty about that.

Q. Isn’t that troubling? Like if the ball-to-ball variability is sort of more extreme than the year-to-year average variability — first of all, how extreme are we talking? That would be a question for you guys. And then also, wouldn’t that have a greater impact in terms of — because the thing that players and front office personnel have been saying to us is, well, we’re all playing with the same ball, but is that not true? Like are certain batters getting — I mean, on any given pitch, they could be getting a ball that is more likely to go out, which would seem to determine the outcome of games with an even greater significance than if the ball was just changing year to year.

ALAN NATHAN: Well, that’s what the data is telling us.

 

At that point Sword jumped in, I suspect because he realized how troubling that all sounded. He noted that it’s always been the case that the ball wildly varies even within games and then added some comments about how Rawlings is the best, there is none finer, etc. etc., echoing the Rawlings’ presidents’ comments along those lines from a few minutes prior.

So what to make of this?

One one level, it makes some sense. Given what the scientists say about how minor variations can create big differences in drag. given how, for that matter, they can’t even identify most of the factors that contribute to drag, and given that balls are hand-made, it follows that there could be big variations.

On the other hand, however, the notion that one ball in a given game can behave like we’ve come to think how 2019 baseballs behave (“juiced” for lack of a better term) and another ball in the same game might be as dead as 2014, is not one anyone has ever really thought about. I certainly haven’t. Have you? I sort of doubt it! We’ve all assumed that balls might be the same for years at a time, change at times — 1930, 1987, 1993, 2015, or 2019 — and that we can track those changed balls by era. Now the balls are said to change, and change big, between pitches.

Which is sort of nuts because the whole years-long exercise of Major League Baseball addressing fan concerns about juiced balls seems to have been aimed at addressing the concerns over randomness. It was aimed at scientifically assuring fans and players that it’s all fair and level and that everyone, to use the phrase MLB officials have used to dismiss such concerns, is “playing with the same ball” Now, in their latest study and in today’s comments, they’re saying that not only is everyone not playing with the same ball, but that we don’t even know whether one pitcher in a game is gonna throw a dead ball and his opponent is going to throw a lively one.

Again: maybe that has always been the case. But it’s not how fans or how players have come to think that the game works. The game, like every other sport, has always been conceived of everyone being on the same field playing with the same basic rules and equipment and applying their physical skills, brains, instincts and research and letting their execution determine who wins and who loses.

Now we know — scientifically — that there is a whole other level of randomness at play.