Editor’s note: An earlier version of this story incorrectly stated which ball the Southern League used in phase one of testing. It used a mudded ball, not one with a gripping agent early this season. The story has also been updated with new information about the Southern League returning to a mudded ball.

Recently, two of Minor League Baseball’s three Double-A leagues entered the second phase of an experiment being conducted by the commissioner’s office.

For all of the 2022 season, the Texas and Southern Leagues have been using the same baseball as major league teams do. This is a change in itself, because MLB uses different balls at most levels of the minors than it does in the majors. But the heart of the experiment lies in what’s being put on the ball before it enters the field of play. Substances from two vendors, the materials science behemoth Dow (formerly Dow Chemical) and a smaller company, Chalkless, were to be tested in different portions of the season, people with knowledge of the experiments told The Athletic.

In the Texas League, one of the gripping agents was applied to every ball for the first two months of the season. During roughly the same period in the Southern League, a mudded ball was used — the standard finishing for baseballs across the sport — making it a control of sorts in the test.

Recently, the Southern League switched over to a ball with one of the gripping agents, a planned second phase of the test. But MLB halted the usage of the ball with the gripping agent in the Southern League after about two weeks, multiple people with direct knowledge of that league said. Both the Southern and Texas leagues are now using the mudded ball.

MLB’s intent was to run the test throughout the 2022 season, conducting one phase with a mudded ball, one phase with one vendor’s substance, and another phase with the other vendor’s grip, in differing order depending on the league, sources said. But following the halt in the Southern League, it was not immediately clear whether MLB will again use one of the vendor’s substances this season or use only the mudded ball for the rest of the year. MLB declined comment.

This is not the first time MLB has conducted such an experiment in a game setting, after introducing one of the substances in the Arizona Fall League last year. Some players, however, have found the process burdensome.

Players in the majors and minors alike have never used bright and shiny balls straight out of the box; they’d be too slick. That’s why mud became standard. MLB has long had a rule forbidding the application of additional substances to the ball aside from rosin, but its enforcement was lax for a long time, and pitchers steadily took advantage — not just to enhance grip, but to improve the performance of their pitches. That problem seemed to reach its apex in 2021, when MLB directed umpires to physically check pitchers for substances regularly, a practice that’s since been modified but is still in place.

Even before last season, though, MLB was investigating whether something better than mud was available. The league wants to see if there’s a way to achieve more consistency from ball to ball, with increased grip that does not simultaneously inflate spin rates and pitcher effectiveness too much. MLB’s goal is to increase the entertainment value of the sport, and increasing balls in play creates more action.

The league does not feel it must make a change, however.

“We have a ball that has served the sport well for decades and we have taken a number of steps to make the baseball the most consistent it has ever been,” said Morgan Sword, EVP of baseball operations at MLB, in a statement. “While we continue to explore solutions to add tackiness without materially increasing spin rates, it’s a very hard thing to get right, and we have set a very high bar for success.”

MLB would rarely want to implement something untested in the major leagues if it can be avoided, hence the test in the minors. But the experiments they’re running in the Texas and Southern Leagues this year have drawn the ire of some players and staff.

“It’s horrible, to be completely honest,” said one pitcher in those leagues of the ball that had a gripping agent applied.

“I hated it,” said a pitcher with another team in those leagues. “A lot of guys had problems with it, for a number of reasons. Sometimes it was fine, other times it was really an issue.

“There was an overwhelming reaction of positivity when they let us start playing catch with these newer balls,” he continued, referring to the standard mudded balls that were brought out last week. “Everybody was pretty fired up.”

MLB declined to provide specific feedback it has received from the leagues, citing a concern for the integrity of the test.

“Our best attempts so far are popular with some and not popular with others, just like our current ball is popular with some and not others,” said an MLB official. “It’s a very challenging effort.”

MLB started to explore alternatives to the current ball before the 2021 crackdown on sticky stuff. Dating to 2019, league officials said, the commissioner’s office was investigating differently designed balls, including some modeled after those used in Japan and Korea. But those builds did not win over enough players in the U.S.

Any additional grip on the ball has the potential to affect the attributes of a pitch, to make it spin and move more than a mudded ball. But MLB is not worried that either Dow Chemical or Chalkless’ agent will create a pronounced effect tantamount to that of, say, Spider Tack, which was particularly strong and a popular choice among pitchers heading into 2021.

“You’d ultimately be making a tradeoff between slight changes in performance and improving consistency and, honestly, player adoption,” a second league official said. “If you really felt like pitchers preferred the ball more, you could live with a small change in spin. If you feel like you’re not getting a real improvement in kind of the reaction from players, your tolerance is going to be lower.”

Before MLB started checking pitchers for illegal substances last season, the ratio of a pitch’s spin to velocity reached its highest point on May 20, 2021, at 24.89. That figure is a seven-day rolling average, and indicated high usage of illicit sticky stuff. By July 1, once MLB started enforcing the prohibition on substances, that figure had dropped to 23.63, a drop the league considered significant. But it climbed back to 24.13 at the end of the 2021 season, and entering Friday was at 24.05.

The higher that ratio is, the more effective pitches become. In the Statcast era, pitchers that have thrown four-seam fastballs at least 500 times and had a spin-to-velocity ratio better than 26.00 have a 22 percent strikeout rate on the pitch. Pitchers sitting below a ratio of 24.00 had a 19 percent strikeout rate on the fastball.

MLB first met with Dow Chemical during last year’s All-Star week. William S. Stavropoulos is the owner of a minor league team in Midland, Mich., the Great Lakes Loons, and also a former CEO of Dow, headquartered in the same city. He brokered a connection, and Dow started to develop a substance specifically for the sport.

Dow is a prominent company, and originally introduced the brand Ziploc, among others. But it also has run afoul of environmental laws, agreeing to pay a $2.5 million penalty in 2011 for violations at its complex in Midland. Last year, another settlement committed Dow to spend $294 million on reducing air pollution in Louisiana and Texas, and there are other examples in its history. MLB declined comment when asked about Dow’s environmental history.

MLB did not address what is in either company’s substances, citing proprietary formulas and the league’s own minimal knowledge of them. Chalkless, which markets to athletes across other sports, brought a product to MLB that was already on the market that has since evolved as the businesses work together. On the bottle of a product Chalkless features on its website, silica silylate is the only listed ingredient. “Doesn’t make things sticky, makes them less slippery,” reads promotional copy on the site.

Chalkless acknowledged it is working with MLB, but did not provide comment for this story.

“As a leading materials science company, Dow works closely with customers around the world to imagine better and tackle tough challenges,” Dow spokesperson Kyle Bandlow said. “However, Dow does not comment on pre-commercial innovations being conducted, owing to the proprietary and confidential nature of such innovations.”

The second MLB official said the league did due diligence on safety matters because pitchers will lick their fingers.

With the regular mudded balls, teams apply the mud themselves before games. But that leaves variability in how much mud gets applied (and potentially, room for teams to try to influence the performance of the ball). Dow and Chalkless are both applying their tack before the balls are shipped to teams, removing a step from the process, which MLB likes.

If MLB did adopt one of the new substances, it would mean moving away from the rubbing mud it has used for almost three-quarters of a century, which comes from an undisclosed location in New Jersey, gathered by a mom-and-pop operation, Lena Blackburne Baseball Rubbing Mud. A message left for the company was not returned by the time of publication.

Ultimately, the new grips have to work and win over players. An MLB official said the commissioner’s office is aware of concerns over the impact of switching between three different balls in a given season.

“We sent the balls to the clubs well in advance of their incorporation into games so that there’s an opportunity to incorporate them before they’re used in games,” the second official said. “And you wish you could do this in a way that wouldn’t require you to actually test in games before you were confident that you had an answer. But unfortunately, we just need a large enough sample and you need feedback from enough pitchers, where it’s really hard to get the information you need … without doing it like this, in games. Where you can see what the impact is.”

The walk rates in both leagues the Texas and Southern Leagues have been elevated compared to the full-season numbers from last year. Pitchers in the Texas League last year walked 4.0 batters per nine innings, and this year were averaging 4.6 entering play Sunday. That’s the highest the walk rate has been in the Texas League in the last 16 years, and the second-biggest increase year-over-year in that time frame.

In the Southern League, the rate has climbed from 3.6 last season to 4.2 per nine entering Sunday. That’s the highest walk rate in the last 16 years, and also the biggest year-over-year increase — and three times as large as the second-largest year-over-year increase.

For comparison, the Eastern League, the only other Double-A league in the sport and a league where testing is not underway, went from 3.6 per nine last season to 3.9 this year.

A player development staffer in the National League said it was true for his team that the tacked-up balls were provided in advance. But a pitcher with a different organization said that was not the case for his group, and that they had to start sneaking balls from the game allotment so they could adequately prepare.

“Especially for the first couple weeks, guys really didn’t have any idea where the ball was going. You could tell,” the pitcher said. “Our relievers who came in from the ‘pen would warm up with a regular baseball because we didn’t have access to the tacked balls outside of the game environment.

“We had to start stealing baseballs from the game ball bag and hiding them in our sweatshirts from the bat boys who are running out the balls, and then we would keep them in a separate bag and only use them in the bullpen for our guys who are about to come into the game so that they would have a feel for where the ball is going.”

During spring training, the commissioner’s office asked some pitchers to throw a bullpen with tacked balls. But that process struck one pitcher who did so as odd.

“They came to me before my scheduled bullpen that day, they were like, ‘Hey, they want to try out some tacked balls, would you be ok with that?’” said the pitcher. “I was like, ‘Sure, whatever.’ And so I go through my catch play before the ‘pen using the ball fine. Feels a lot different than a normal baseball, but that’s kind of what I’m expecting. I get up on the ground and the first pitch that they want me to throw is a slider or something, and all the pitching coaches are like, whoa whoa whoa.

“In a bullpen environment, it’s pretty much established that you start off with fastballs and work into the ‘pen, and they were like, ‘Well, we have this predetermined script that we have to follow.’ And I was basically like, ‘You know, this is my bullpen, I’m going to throw my five fastballs or whatever, and if it messes up your data, I really don’t care.’ So that was the first sign that like these really guys really don’t know what it’s like to be a pitcher. They’re just here trying to collect data in a vacuum.”

Said an MLB official in response: “There were baseball people involved in every step of the test, including a former Major League pitcher, to ensure player safety considerations. The test was designed to be a collaborative environment, with pitchers fully warm and ready to go before beginning the test sequence, and player preference incorporated.”

Both pitchers said that the tacked-up balls were inconsistent.

“I don’t know whether it was, if it was extremely humid it made it worse, if it was extremely dry it made it worse, or you need to have just a little humidity?” one said. “Often times I could look in my glove after an outing and it would just be coated — looked like someone sprayed baby powder in my glove from all of the powder that was coming off the ball into my glove and into the catcher’s glove.”

Said the other: “The problem that I had comes when the balls are not stored properly … all of the spray that they put on it kind of deactivates after a while, and then it just turns into dust and it feels like you’re throwing a snowball, basically.

“It wears off on the ball after about three pitches, three to four pitches. The ball goes back to feeling like a normal pearl, like an old-school regular baseball. Which is what I prefer. And so I started telling all my infielders, like, ‘Hey, if a ball gets hit’ — usually they want to throw it out and get you a new ball. But in reality, the more time you can throw those balls the better-feeling they become.”

Club staff, meanwhile, have concerns from a player development perspective.

“Negatively impacting spin rates, negatively impacting vertical movements, spin efficiency,” the player development staffer said of using a ball with a gripping agent. “I think there was some unintended movement of offspeed pitches for that reason. But it definitely negatively impacted fastballs on multiple occasions.

“There were some guys who were really really affected by it, some guys who weren’t. For the guys who were really affected by it, they’ve pitched a couple times (with the mudded ball) and have been the person that we knew they were going to be. It’s pretty frustrating for us in a lot of cases, where I don’t think we are getting a true evaluation of a guy’s total ability. Because he’s being handicapped by something that’s completely out of his control.”

One of the reasons MLB chose Double A for the tests this year rather than a lower level, an MLB official said, is to minimize the number of times pitchers switch balls in their career. Had MLB done the test at the Single-A level, then pitchers climbing the ranks would have had to use a major league ball at Single-A, a minor league ball in Double A, then a major league ball at Triple A or the majors.

The club staffer noted that some pitchers who normally didn’t have control problems newly appeared to.

“A big issue we ran into with a few of our guys, guys who never had issues with walks or command or feel or anything like that, basically as soon as you get sweaty the ball would just get slippery,” the staffer said.

It’s not just the actual ball with a gripping agent applied that has thrown players for a loop. The fact that they are participating in an experiment does not sit well with some. Both pitchers, as well as one player agent, volunteered the same term: “guinea pigs.”

Other rule changes are also ongoing in the minors, including tight enforcement of the pitch clock, which one pitcher noted can have some interplay with the ball.

“When we first started getting the new balls, you could doctor them on the spot how you wanted to if you just rub them up, or if you swipe the grass with your hand and then rub them up for 10 seconds. But the pitch clock didn’t allow for that,” one of the pitchers said, describing attempts to remove some of the grip from the ball. “That’s a scenario where throwing multiple rule changes in at once really screwed us.”

MLB has been soliciting feedback through some in-person visits to teams, and through questionnaires emailed to players.

Were MLB implementing a test in the major leagues, it would at the very least be discussed with the Major League Baseball Players Association. But the MLBPA, which declined comment, does not represent most minor league players. Harry Marino, the executive director of the non-profit Advocates for Minor Leaguers, criticized the experiment.

“In any fair system, Minor Leaguers would have to consent to being used as test subjects for prospective Major League rules changes,” Marino said in a statement. “In exchange, Minor Leaguers would be able to negotiate for increased compensation — after all, the data gathered from rule experimentation with Minor League players is immensely valuable to MLB. Instead, MLB imposes such experimentation without consent, at no additional cost. This is fundamentally unfair and needs to change.”

Speaking to a group of sports editors, including those from The New York Times, Manfred in May left the door open for a new substance to be in place in the majors for 2023. This month, the first league official said that while it would not be impossible to implement a change for next season, it’s not likely at this point.

It’s unclear whether MLB would be able to unilaterally implement a new substance without approval of the Players Association. It likely would fall under the jurisdiction of a newly formed competition committee that includes appointees from both the union and the league, and on which the league controls the majority votes. But at least for now, industry sources suggest the process is unlikely to arrive at a showdown or a point where MLB moves without player support. MLB and the union have been in touch about the experiments, and MLB typically would not have incentive to make such a massive change without major league players’ buy-in.

Said one of the pitchers: “Pitching at the highest level is hard enough with as few variables as possible. And I think that this is not an insignificant variable that’s been thrown into the mix.”

The player development staffer said if he had the choice, he would halt the experiment.

“Double A is just too high of a level to start doing this,” he said. “In my opinion, every ball should be the same ball for every single level. … Doing it to these guys who are right on the cusp of getting into the big leagues seems pretty irresponsible to me.”

The Athletic‘s Eno Sarris contributed research to this story

(Top image: Wes McCabe / The Athletic; Photo:  Jeff Gross / Getty Images)