Commissoner Rob Manfred discussed progress on developing a properly tacky baseball. A pristine ball might cause another problem, however:

“Like everything in baseball, when you inch towards a solution, you figure out another problem,” Manfred said. “The baseball, if we get there with the Dow people, would be a pearl, right? A pure white baseball. I think if you take hitters and pitchers out front here and ask ’em what they think of a pure white baseball, you’re going to find out that it’s a pretty controversial topic. So not only do we have the science that we’re continuing to work on but we’re going to have to get over that sort of policy issue of: Is a pure white baseball a good thing?”

ESPN.com

I don’t know what batter objections would be to the ball, but a very clean ball might be much tougher for pitchers to secretly scuff.

Reference in the headline:

Don’t Worry About the Vase likes the idea of the Goldilocks baseballs in post-season games:

As someone who has previously gambled on the number of runs in various baseball games, I was not even a little bit surprised to see MLB differentially using different baseballs based on when they would benefit from having more exciting games.

I also mostly do not mind it, especially with regard to the postseason. Thanks to various dynamics of teams, incentives and scheduling, and the ability to run your pitchers in an unsustainable way because there is no tomorrow, postseason baseball games do not have enough offense in them. It is not good for the game. You want the opposite, where the games the diehards watch can be quick pitchers’ duals that true fans appreciate and then you put a more superficially exciting face forward for the public, and those who don’t care about either team still playing, at the finish line. I’d prefer that they not pretend they are not doing it, but I understand why they can’t come out and say it.

TheZvi.Substack.com

Maybe MLB should randomly assign one of the three types of balls to every game, and not tell the teams which one they are getting. This might prevent hitters and pitchers from falling into undesirable patterns, like swinging for the fences because the ball is juiced.

Tom Tango models the sweet spot of the bat.

The AP obtained a memo explaining how team are to handle their game balls:

MLB is instructing that “each club staff member involved in the process should apply mud in a uniform manner ensuring the same mud-to-water ratio is applied to each ball. Rubbing mud should be applied to each baseball for at least 30 seconds, ensuring that mud is rubbed thoroughly and consistently into the entire leather surface of the ball.”

After rubbing, balls are to be put back in Rawlings boxes, with dividers between each, and returned to the humidor until the home team’s gameday compliance monitors gets them for game use. In an effort to reduce time in ball bags, balls are to be taken from the humidor 15-30 minutes before the scheduled start, and then no more than 96 balls at a time.

When needed, up to 96 more balls may be taken from the humidor, and they should not be mixed in bags with balls from the earlier bunch. A bag must be cleaned with a damp cloth and then a dry cloth before it is used “to make sure there is no excess residue, dust or moisture.”

Chron.com

That is a complicated process. I hope MLB comes up with a pre-treated ball, because that seems rather expensive process.

MLB needs to ritualize this. They need a song that the ball rubbers can sing as they massage the mud into the leather, like this:

How about:

Mud, on the leather.
Dampness in the box.
Mud, on the leather...

Tom Tango on how baseballs vary:

MLB sent out tacky balls for players to evaluate:

Rich Hill confirmed that the New York Mets reviewed the prototypes about a week-and-a-half ago. Los Angeles Dodgers pitchers were also shown the balls while playing in New York, and the San Francisco Giants are expected to receive them during their series against the Mets this week as well.

Spootrts.Yahoo.com

The trick will be to find a tackier ball that doesn’t increase spin. That’s been difficult so far, and MLB batters may need to accept some extra-spin to give the pitcher the grip they desire.

Exploring Baseball Data With R presents some good evidence that the ball is not carrying as much as during the same period in 2019:

• There is some evidence that batted balls are hit harder in 2021. But by comparing 2019 and 2021 rates across different regions of the (launch angle, exit velocity) space, the rates of hard-hit balls seem pretty similar in the two seasons.
• Our comparison shows that the home run rates in balls in different regions are not the same. The 2019 balls appear to be carrying further, leading to higher home run rates. In other words, the drag coefficients appear to be higher in 2021.

That is indeed what MLB was trying to accomplish. Balls hit at the same launch angle with the same exit velocity are not carrying as much.

The changes made to the major league baseball intended to counter a decrease in drag appear to have worked:

As part of the tweaks, Rawlings loosened the tension of the first three wool windings within the ball. The change lessened the ball’s weight by less than 0.1 of an ounce without altering its size, and decreased its coefficient of restitution (the bounciness of the ball), which in recent seasons had trended to the high end of the range MLB tries to maintain.

“Measurements from both Rawlings and the UMass Lowell test laboratory show that the desired effect was achieved,” Alan Nathan, a professor emeritus of physics at the University of Illinois at Urbana-Champaign, told Sportico in February. 

This was the lowest scoring spring training since 2015, and home runs dropped as well. As reported earlier, MLB will be cracking down on using substances to increase spin rates on the ball. So the ball won’t be traveling as far for the batters, and maybe not breaking as much for the pitchers. The hope is that this results in more line drives in the field of play. We’ll see.

Players will be able to use tablet computers in the dugout to watch previous plate appearances in 2021. Video was banned after the Astros sign stealing scandal and the Covid pandemic limiting people in the video room:

It was a jarring change for some hitters during a down year for offense during the pandemic-shortened season. But Major League Baseball has cleared the way for the return of in-game video on dugout iPads beginning on Opening Day, with catcher signals obscured by a computer program.

ESPN.com

That sounds like a good solution to the problem.

MLB decided to make the ball a bit looser in order to cut down on home runs:

In an effort to better center the ball, Rawlings has loosened the tension on the first of three wool windings within the ball. Its research estimates the adjustment will bring the COR down .01 to .02 and will also lessen the ball’s weight by 2.8 grams without changing its size. The league does not anticipate the change in weight will affect pitcher velocities.

The memo did not address the drag of the baseball, which remains a more difficult issue to control.

ESPN.com

I think this is a good move, and it’s especially good that it got leaked, so everyone knows what to expect. Home runs influence the other true outcomes. Pitchers are more likely to work around big sluggers, raising walk totals. With a lower chance of a home run, some players may try to put the ball in play more, cutting down on strikeouts.

We will see. MLB expects the difference to be subtle. Maybe it will be enough put a little more action in the game.

David Kagan at The Hardball Times reviews the math of how seam height changes the carry of the ball. A missing sub-thread in the thread used for stitching can add over two feet to the travel of the ball.

That said, consistent year-to-year variations that appear to continually increase the number of home runs are radically changing the game. From 2013 to last season, the seam height has dropped by about 0.005 inches. In addition, according to the report, the seam height problem is only 35% of the total decrease in drag.  Until there is a good explanation for seasonal changes, some will continue to claim there is a “seamy” side to baseball.

THT.FanGraphs.com

Note that pitchers can detect this change, and their complaints that the seams are lower is true.

MLB released the independent study of why home run rates changed in recent seasons on Wednesday, today. Here is the article, and I urge you to read the complete explanation. It is very accessible. The article indicates nothing changed in the manufacture of the ball. There is a great deal of ball to ball variability, and that variability over the entire season led to a lower drag co-efficient. That accounted for about 60% of the home run increase in 2019. The other 40% came from batters changing to more favorable launch angles combined with higher exit velocities.

One of the most interesting things to come out of this study is the creation of new techniques to measure the height of seams down to the thickness of a piece of paper:

The apparatus used previously to measure the drag and seam height were significantly modified, resulting in an improvement to both the precision and accuracy of the measurements. These improvements, when combined with the large sample sizes for the 2018 and 2019 seasons, allowed a statistically significant determination of differences of yearly mean values as small as 0.005 for Cd and 0.0016 inches for seam height.

MLB.com

It turns out a very tiny difference in seam height leads to a large change in the coefficient of drag, Cd above. The seams are not the only reason for the change in drag, however.

Figure 8 shows a nice summary of what happened in the last three seasons. In 2017, drag was down, leading to a record setting year for home runs. In 2018, batter improved their launching of the baseball, but drag was up, countering the launch. In 2019, launch and drag shot up together, and we saw team and league records fall.

The committee also has a number of suggestions for better monitoring the ball, and picking up on changes before things get out of hand.

David Kagan provides a good definition of a juiced ball, and shows that today’s ball is not juiced enough to explain the increase in home runs.

There are two distinct interactions that determine the distance a baseball will travel. The first is the collision with the bat, which determines exit velocity of the ball, the launch angle, and the spray angle, as well as the spin on the ball. The second interaction is between the air and the ball during the flight.

The drag coefficient is only relevant to the flight of the ball and has nothing to do with the ball-bat collision. The term “juiced ball” doesn’t refer to properties associated with the flight of the ball but instead is associated with the collision. Drag is associated with the flight of the ball, while a juiced ball is related to the ball-bat collision.

THT.FanGraphs.com

His collusion conclusion is that “juicing” is only adding two feet of flight to the ball, compared to the 15.4 feet extra the ball is traveling.

MLB pushed back their study of why the baseballs flew farther this season to include post-season balls.

I’m very interested to see what they find. I seem to be in the minority that MLB didn’t intentionally juice the ball.

Physics professor David Kagan examines the drop in the drag coefficient of the current baseball. His calculations of the number based on the probability of a well struck ball leaving the park agree with measurements by the lab that authenticates baseballs.

Now we are prepared to get back to the original question: Why is it so hard to figure out the cause of the drop in the drag coefficient?  Back in my garden, I can’t easily detect a decrease in the average size of a tomato because the tomatoes themselves vary in size much more than any change in the average size. In the lab with a bunch of baseballs, we need to explain a 3% change in drag coefficient when the drag coefficient naturally varies over a 40% range.  

If I was really concerned enough to find out if the fertilizer was worth the money, I would need to measure the size of very large numbers of randomly chosen tomatoes both before and after the fertilizer.  That way, I would be very certain of the average size in both cases. Similarly, if you suspect some property of the ball (seam height, surface roughness, etc.) has changed, you need to know the average value of that property both before and after to a high degree of certainty.

The point is, you can’t just grab a few baseballs and test to see if some particular property of the ball is the source of the change in drag coefficient.  After all, you may have randomly grabbed some that have too high a drag coefficient and get really screwy results. The underlying issue is that we’re looking for a needle in a haystack–and you need to examine a lot of hay before you find the needle.

THT.FanGraphs.com

Maybe the right thing to do now is stop asking why, and start asking what would bring the drag coefficient up again.

Note, too, that a lot more balls were well hit in 2019, so the increase in home runs isn’t all on the baseball.