power surge / juiced baseballs 2018

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It’s been a year-plus of speculation, increased home runs, and denials by the league and the commissioner, but it now looks as if there’s actual proof that baseballs have actually changed in recent seasons leading to the offensive spike.

FiveThirtyEight’s Rob Arthur, who along with The Ringer’s Ben Lindbergh has led the way with juiced ball research, tweeted on Wednesday “There’s now evidence that every part of the baseball has changed: core, yarn, and surface. I’m looking forward to that report from MLB’s task force.” Arthur’s report with the proof of this hasn’t published just yet, but Arthur’s commitment to this study is enough to think he has something concrete here.


ice cream social justice (Dr Morbius), Thursday, 15 March 2018 21:08 (one year ago) Permalink

they should put even more juice in the balls imo

ciderpress, Thursday, 15 March 2018 21:12 (one year ago) Permalink

two months pass...

MLB's own commission confirms that the baseball has changed, and is responsible for the home run surge. Largely vindicates three years of study by me and many others. https://t.co/wndIWTcs20

— Rob Arthur (@No_Little_Plans) May 24, 2018

mookieproof, Thursday, 24 May 2018 18:41 (one year ago) Permalink

Study Finds Change in Aerodynamic Properties of the Baseball, But No Significant Change in Regularly Measured Ball Properties

Major League Baseball has received the results of a study conducted by a committee of scientists on the causes of the increased home run rate in the game since 2015. The committee, assembled by Commissioner Robert D. Manfred, Jr. in August 2017, was comprised of the following experts:

Alan Nathan (Chairman) – Professor of Physics Emeritus, University of Illinois
Jim Albert – Professor of Statistics, Bowling Green State University
Jay Bartroff – Professor of Mathematics, University of Southern California
Roger Blandford – Professor of Physics, Stanford University
Dan Brooks – Owner of BrooksBaseball.net
Josh Derenski – Ph.D Student, Marshall School of Business, University of Southern California
Larry Goldstein – Professor of Mathematics, University of Southern California
Peko Hosoi – Professor of Mechanical Engineering, Massachusetts Institute of Technology
Gary Lorden – Professor Emeritus of Mathematics, California Institute of Technology
Lloyd Smith – Professor of Mechanical & Materials Engineering, Washington State University

The committee investigated a number of hypotheses, including the properties of the baseball, weather conditions and changes in player behavior. The research included a detailed analysis of Statcast data, as well as an investigation of the properties of the baseball that can affect home run production, including an inspection of Rawlings' production plant in Costa Rica. The committee set its own agenda and arrived at their own conclusions and recommendations, independent of the Commissioner's Office.

The committee concluded that the increase in home run hitting since the 2015 season was due, at least in part, to a change in the aerodynamic properties of the baseball (i.e., reduced drag for given launch conditions, as opposed to a change in launch conditions). That conclusion is supported by their analysis of Statcast data, a physics-based model that the Committee developed, and laboratory testing of game-used baseballs from before and after the increase in home run rate. The Committee did not find any change in the size, weight, seam height, or COR of the baseball that would explain the increase in home runs. Though the Committee was unable to conclusively prove the exact cause of the reduced drag since the 2015 season, they offered hypotheses including that the rubber pill may be more centered within the baseball since 2015 and that the ball may be staying rounder while spinning since the 2015 season.

Importantly, the committee also concluded that no change to the materials or manufacturing process, whether intentional or unintentional, has played a significant role in the home run surge.

Based on the results of the study, the Commissioner is taking the following actions:

1. Monitoring of Temperature and Humidity Conditions. The Commissioner's Office is monitoring temperature and humidity in the ball storage locations of the 30 ballparks and will work with the committee on whether to require the use of humidors at all ballparks for the 2019 season.

2. Review of Production Specifications of Baseballs. The Commissioner's Office is working with Rawlings to make updates to the existing production specifications of baseballs and to develop additional specifications for the aerodynamic properties of the ball.

3. Perform Aerodynamic Testing on Baseballs. In addition to the existing testing protocol, the Commissioner's Office is working with the committee to develop a set of aerodynamic tests for game baseballs.

4. Create Standards for Mud Rubbing. The Commissioner's Office is providing Clubs with guidance on the appropriate mud rubbing of baseballs, which will be enforced by the umpires.

5. Formation of a Scientific Advisory Council. Some members of the committee will continue to advise the Commissioner's Office on issues related to baseball performance, as well as other science-related topics.

Commissioner Manfred said: "I thank the committee for all of its hard work on this important issue. Based on the results of their study, I am accepting their recommendations immediately and look forward to their continued guidance in this area."

The committee's complete report accompanies this press release, along with a more concise summary furnished by best-selling author and theoretical physicist Dr. Leonard Mlodinow, who provided support and assistance to the committee.

mookieproof, Thursday, 24 May 2018 18:55 (one year ago) Permalink

9. They don't know why the ball is carrying farther.
Further testing focused on the ball's surface roughness and center of gravity is ongoing. But the report does not rule out the possibility that manufacturing advances have contributed to the reduced drag by creating a more spherically symmetrical ball with a more properly centered pill (which would in theory lead to a lower drag). Nathan said the tools available to the researchers are not precise enough to properly determine one way or another whether that was the case.

"Rawlings is always trying to improve the manufacturing process to make it more uniform," Nathan said. "So the interesting question that comes up is whether the goal should be to improve the manufacturing process or to keep the ball performing exactly the way it is, regardless of whether it's improved or not."

Nathan said he understands that there will be people unsatisfied with the committee's incomplete answers.

"As a scientist, it is what it is," he said. "We don't want to claim more than we can legitimately claim. To admit that there are things that we don't know, we don't like to have to admit that. But that's what we have to admit."


the ignatius rock of ignorance (Dr Morbius), Thursday, 24 May 2018 19:01 (one year ago) Permalink

Create Standards for Mud Rubbing

mookieproof, Thursday, 24 May 2018 19:28 (one year ago) Permalink

It could be what they're feeding the cows!!

It was you, Bossy...

the ignatius rock of ignorance (Dr Morbius), Saturday, 26 May 2018 14:19 (one year ago) Permalink

two months pass...

i feel like i haven't heard anything about this for a while ... is it still happening this season or was last season an outlier?

na (NA), Friday, 24 August 2018 16:26 (ten months ago) Permalink

seven months pass...

Rob Arthur:

We’re only a week into the 2019 season, but the drag numbers so far are among the lowest recorded in the last calendar year. With apologies for gory math, the current 2019 season average drag coefficient (the red line) would be below the 95 percent credible interval (the shaded area) for about nine-tenths of the 2018 season. (I used a Bayesian Random Walk model implemented in INLA to calculate these credible intervals, averaging the drag numbers in each game and adjusting for park.)

There were only a handful of six-day stretches in 2018 that had drag numbers below what we’re seeing now, and most were in late June and early July. All of this means that 2019’s data so far is quite a bit different than what we saw through most of last year....

On the one hand, it’s only been six days, and we don’t quite have the statistical basis to say that these drag coefficients are unprecedented compared to 2018. On the other hand, we’ve witnessed about 5,000 fastballs so far this season, so it’s not as if our sample size is small. At least so far, the baseball has played like it’s much more aerodynamic than it was last year. In fact, the current drag coefficient is really only comparable to 2017, when the baseballs were more aerodynamic than they had been in at least a decade.


a Mets fan who gave up on everything in the mid '80s (Dr Morbius), Friday, 5 April 2019 15:40 (two months ago) Permalink

the two triple-a leagues are (finally!) using MLB-regulation baseballs this season. it's only been two weeks, but the early indications are clear:

Last April, Triple-A hitters homered once every 47 plate appearances. As the weather warmed up, so did the home run rate. Over the course of the entire 2018 season, Triple-A hitters homered every 43 plate appearances. So far this year, they are homering every 32 plate appearances. Triple-A hitters are hitting home runs at a rate of 135 percent of last year’s rate.

That’s an amazing stat and one that should strike fear in the hearts of pitchers around the International League and the Pacific Coast League. After all, April is usually the month that turns home runs into long flyouts. It’s cold. The ball does not travel.

Because the rest of the minor leagues have continued to use the less-expensive traditional MiLB ball, we have a control group that allows us to see just how much difference the MLB ball has made.

Across the rest of the minors, the early season numbers are right in line with what would be expected. Offensive numbers start slow and then heat up with the weather. Across Class A and Double-A, hitters are hitting .231 (low Class A) to .234 (high Class A and Double-A). Those batting averages are 17 to 20 points below where they ended up for 2018. Slugging percentages are down roughly 30-35 points from last year’s averages as well. And home run rates similarly are down. In the first couple of weeks of the season, the home run rate at those three levels ranges from 81.6 percent of 2018’s numbers (low Class A) to 88.8 percent (Double-A).

That’s what we would expect. As the temperatures heat up, the ball flies further and offensive numbers go up. Those numbers have dipped a little more than they did for all of April last season, but within similar ranges. At the end of last April, all four full-season leagues were hitting home runs at 90 to 97 percent of their end of season rates.

Remember how Triple-A hitters are homering every 32 plate appearances? Just a level lower, Double-A hitters are homering every 53 plate appearances. Last year, MLB hitters homered every 33 plate appearances, similar to this year’s Triple-A rate. But the Double-A home run rate is comparable to a level we haven’t seen in the major leagues since the strike-shortened 1981 season.

if this continues, it is going to be absolutely insane in places like reno/albuquerque/las vegas this summer

mookieproof, Thursday, 18 April 2019 19:51 (two months ago) Permalink

nine homers hit in reno last night, with no wind

mookieproof, Friday, 26 April 2019 16:01 (one month ago) Permalink

AAA Home Run Totals:
April 2018 - 551
April 2019 - 960
AAA leagues started using MLB baseballs in 2019.

— Minor League Stories (@MinorsTeamNames) May 1, 2019

mookieproof, Wednesday, 1 May 2019 16:13 (one month ago) Permalink

one month passes...

3 ppl in my beer league softball hit their first career home runs yesterday, two of whom are in their 4th years i think and the third idk how long he's played... so this problem runs all the way from the bottom to the top is what i'm saying

km not doin typos anymore (Will M.), Monday, 3 June 2019 14:49 (three weeks ago) Permalink

your league obviously needs a humidor

mookieproof, Monday, 3 June 2019 14:55 (three weeks ago) Permalink

a good start would be more than two balls so that a particularly foul-y at-bat doesn't take 3 minutes to continue on the third pitch

km not doin typos anymore (Will M.), Monday, 3 June 2019 17:44 (three weeks ago) Permalink

read a conspiracy theory that MLB intentionally juiced the ball to create more offense to make games last longer so that they'd have more ammunition regarding the need to improve pace of play in MLBPA negotiations

na (NA), Tuesday, 11 June 2019 18:15 (one week ago) Permalink

assigning way too much creativity to Park Ave i think

a Mets fan who gave up on everything in the mid '80s (Dr Morbius), Tuesday, 11 June 2019 18:37 (one week ago) Permalink

Todd Frazier throws his bat in disgust thinking he popped out. The juiced ball had something else in mind ⚾️ 💉 pic.twitter.com/gWCPWStJku

— Gotham Sports Network (@GothamSN) June 22, 2019

mookieproof, Saturday, 22 June 2019 22:36 (two days ago) Permalink

thanking u for screen name

Manfred Hemming-Hawing (WmC), Sunday, 23 June 2019 15:23 (yesterday) Permalink

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