MLB secretly used two different types of baseballs last season, according to report

Attempt to deaden the ball was undermined by use of old baseballs

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Photo: Getty Images

Can’t we go six months without a scandal in Major League Baseball? Just six months. That’s all I’m asking for.

Cheating has become ingrained in baseball culture. Whether it be PEDs, using high-speed cameras to steal signs, or spider tack, players have always found ways to get an upper hand on the baseball diamond. Major League Baseball is supposed to be the governing body of the sport. They’re supposed to crack down on cheating and punish anyone who gets caught breaking the rules. However, in light of a report yesterday from Business Insider’s Bradford William Davis, Major League Baseball did some cheating of its own in 2021.


According to the report, MLB used two different styles of baseball in various parks throughout all of 2021, and they didn’t tell a single soul. Even MLB team executives had no idea. However, some players could tell there was something off with the game-used balls last season.

Two-time All-Star reliever Sean Doolittle told Business Insider that while watching games from the bullpen in 2021, there were several instances where he and his fellow relievers were surprised that certain fly balls ended up leaving the yard. It happened so often that Doolittle couldn’t help but start wondering what tomfoolery was going on.


“There were a few instances over the course of the [2021] season where, you know, we’re sitting in the bullpen watching the game or whatever. And, like, a home run gets hit, and you’re kind of, like, surprised that it got out. And so, like, you’re looking at it and you’re like, ‘That’s kind of weird.’ ... It can only happen so many times before you start, like, questioning things.” — Sean Doolittle

This observation from Doolittle, who pitched for Cincinnati and Seattle last season, is bolstered by the memo sent out to all 30 Major League clubs in February stating that the production of game-used balls was going to be altered for the 2021 season. The memo sent out by MLB did not detail how production would be changed, but multiple sources told The Athletic that the change was being made in order to reduce the rising home run rates the league had seen in previous years. That’s all fine and well, but when certain events happened in MLB games last season, such as Joey Votto’s seven-game home run streak, heads turned and tilted at how some of Votto’s batted balls actually appeared off the bat. Several of his home run swings were viewed as nothing more than weak flies off the bat. The launch angle and exit velocity on Votto’s first home run of the streak indicated that the ball had less than a 10 percent chance of actually being a home run. On the other end of the spectrum, Votto’s streak finally ended after he hit a long single off the wall with an exit velocity of 110 miles per hour at an angle of 24 degrees. Of all balls hit at that speed and at that angle in 2021, only two ended up as singles, and almost 92 percent all left the ballpark.

These improbable results on two very differently hit balls led Meredith Wills, a Society for American Baseball Research (SABR) award-winning astrophysicist, to measure hundreds of different game-used balls from half the league’s ballparks. While Wills did find that the league had introduced the new ball with a lighter center to its rotation, the league also allowed older model balls to remain in the rotation as well. The kicker? The league did not tell its owners, players, or fans which balls would be used in each game.

It’s somewhat expected that Major League Baseball would go behind people’s backs like this. After MLB purchased Rawlings in 2018, many suspected that it was only a matter of time before the league started manufacturing balls to fit whatever narrative the league wanted to push. Well, it appears that the narrative MLB wanted to push in 2021 was, “Hey, we know there have been a lot of home runs. We’re trying to fix it, but also, we don’t want to fix it.”


This newfound data had me thinking “If Wills dissected balls from half of MLB’s ballparks, how many ballparks experienced huge drop-offs or rises in home run rates?” Here is a graph detailing the difference between the home run rate in each ballpark for 2021 and the home run rate for those same ballparks from 2016-2020.

Image for article titled MLB secretly used two different types of baseballs last season, according to report

The faded red line is the perfect line. If 2021 played out perfectly, we’d see every team on that exact line. However, that’s too much to expect. In general, the teams look pretty good. The graph follows the line relatively well. The Washington Nationals fell exactly in line at the tenth spot in the league, and the teams near the top of the league from 2016 to 2020, tended to be near the top of the league last season as well.

There are some outliers like the Chicago Cubs who ranked 22nd in home run factor between 2016 and 2020 (91.4 — 100 is league average), but ranked sixth in 2021 (111), the ballpark’s highest home run factor since 2015. There’s also the Detroit Tigers, who ranked 17th in home run factor between 2016 and 2020, but ranked dead last in that category in 2021. To be fair though, Comerica Park’s home run factor has been slowly falling since 2016, but the drop from 91 in 2020 to 78 in 2021 is still too big a drop to be merely coincidental.


Clearly, there are some issues with the graph. For example, I measured the home run factor for the Texas Rangers between 2016 and 2021, but the Rangers moved across the street from Globe Life Park to Globe Life Field in 2020. From 2016 to 2019, Globe Life Park was one of the most hitter-friendly parks in the league, averaging a home run factor of 112.5 during that span. However, since the team moved, Globe Life Field has been below league-average in home run factor both seasons (89 in 2020; 97 in 2021). Similarly, the Atlanta Braves moved from Turner Field to Truist Park in 2017. Turner Field had a home run factor of 72 in 2016 (tied for the second-lowest in the league that season). Truist Park hasn’t had a home run factor lower than 80 since.

All in all though, 2021 doesn’t seem too different than years past, so as much as Mets fans might want to blame their poor offensive season on their players being forced to hit the new design, lighter center balls that don’t fly as far, the home run factor in 2021 wasn’t too far off from their figure over the five years prior. Obviously, MLB can’t be excused for going behind its team’s backs in order to push its agenda, but it doesn’t seem like their decision to use two different styles of balls really affected how hitter/pitcher-friendly each ballpark was in 2021