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These days, everybody digs the long ball. Since halfway through the 2015 season, Major League Baseball has seen a sustained power surge that in 2017 broke the all-time record for home runs in a season. The spike has been not just unprecedented, but also unexpected. Just before the inflection point in 2015, offense was down so much that some writers began proposing rule changes to save the game. After the season’s second half saw a sudden spike in home-run rates, it wasn’t long before many observers arrived at an explanation: The balls were different, altered in ways invisible to the naked eye but enough to make more fly balls clear the fences. In other words, they argued, the balls were “juiced.”

Since then, writers and researchers have used various methods—analyzing publicly available statistics, X-raying baseballs, and firing them out of cannons—in an attempt to confirm the juiced-ball hypothesis. The differences, Rob Arthur of FiveThirtyEight told me, are so minuscule “even someone intimately familiar with the baseball probably wouldn’t detect them.” The seams, studies say, are flatter, reducing air resistance; the rubber-and-cork cores, scans show, are lighter by about half a gram. That may sound insignificant, but on such a small object, the weight difference alone can make a ball fly six inches farther. Combine a few such tweaks and players who previously had “warning-track power”—enough to hit the ball to the wall, but not over it—become home-run hitters, and the league sees a historic increase in offense. Other factors may contribute to the home-run bump (for example, the gradual climate change–induced rise in temperature has a slight effect). But Arthur, who co-authored an intensive investigation on the subject, says controlling for these other factors doesn’t nearly account for the whole increase, leaving the juiced ball the most compelling explanation.

With the body of evidence growing, many observers—and even some players—have begun looking to the league for a response. Asked about the controversy, a league spokesman provided a statement MLB Commissioner Rob Manfred made at a press conference in late February: “The baseballs are a really important topic. We have actually had a postseason-long project, involving independent experts, ongoing. That project is not quite complete. At the conclusion of that project, we will have both information available as to the results of the process and some recommendations as to what we’re going to do going forward.” And while MLB’s history suggests a proactive approach may prevent the controversy from growing, factors unique to the current situation support the league’s wait-and-see attitude.

In general, MLB has a history of openly tinkering with the physical dimensions of the game, including to address fluctuations in scoring, without much controversy. The league publicly introduced balls with cork centers at the end of the 1910 season; the next year, home runs, though vanishingly rare by modern standards, increased by 50 percent. A decade later, the long stretch of defensive dominance now called the “deadball era” ended after the league again changed the ball’s composition and mandated teams more frequently replace balls so wear and tear wouldn’t change their flight paths. Because each hit makes a ball softer, less round, and less bouncy, the changes also helped increase offense. And after 1968’s low-scoring “Year of the Pitcher,” MLB lowered the pitcher’s mound to benefit hitters.

Those changes aren’t confined to the distant past. In 2002, the Colorado Rockies introduced humidors to counteract the offense-enhancing effects of Denver’s altitude; the Arizona Diamondbacks did the same this year to combat Phoenix’s aridity. Some teams, most recently the Rockies and the Miami Marlins, have actually adjusted the fences in their stadiums between seasons to tweak home-run rates.

If anything, a slow response to an offensive surge could come back to haunt the league. Neither the players implicated nor MLB itself has escaped the stigma of the steroids era, which was already becoming a major scandal by the time the league began testing for performance-enhancing drugs in 2003. Then there’s 1987’s “Rabbit Ball” season, a still-unexplained spike in offense that coincided with the league shifting baseball production from Haiti to Costa Rica—but that subsided just as inexplicably the next year. Though discussions of that season don’t reach the same level of animosity as those surrounding performance-enhancing drugs, the mystery persists, making the “Rabbit Ball” a touchstone for more recent juiced-ball allegations.

Still, it’s easy to see why the league is taking a measured approach. To begin with, nobody really knows who could be behind the alleged juicing. One theory, grounded in the home-run surge’s fortuitous timing, is that MLB itself made the change. Ben Lindbergh, who worked with Arthur on early juiced-ball research and now writes for The Ringer, considers such speculation unfounded: “I’ve never seen any evidence that it was something directed by the league, and it seems ill-advised to try to cover something like this up,” he told me. Such a cover-up could generate a controversy bigger than the crime itself, as happened with Japan’s Nippon Professional Baseball, whose commissioner resigned in 2013 after the league copped to secretly juicing the ball.

Given the lack of a clear culprit, MLB may also genuinely believe the research it has commissioned could disprove the juiced-ball hypothesis. Lindbergh is skeptical, noting that the league provided him data it believed would quell the rumors last year, only for additional testing to confirm the balls were, in fact, different.

On a more basic level, there isn’t much immediate incentive for the league to be more assertive. After all, Arthur observed, unlike a humidor, which “is instantly and obviously going to be present and be the subject of knowledge of the grounds crew, the players, and the administrative staff,” a juiced ball isn’t visible to the naked eye. Though “you do hear pitchers saying all the time that they can feel the difference,” said Lindbergh, anybody who doesn’t hold baseballs for a living “has to send these balls to a lab and dissect them or MRI them or fire them out of a cannon to detect some small difference in the way they behave.”

Moreover, it’s hard to see the juiced ball becoming a steroids-level scandal. Part of the problem in the 1990s and 2000s, Lindbergh noted, was that “PEDs were benefiting some players and teams more than others. With the balls, though, everyone’s playing under the same conditions.” Arthur agreed: “The steroids era had all these crazy outlier performances, and that hasn’t materialized in this era. Nobody’s home runs went up by 80 percent. They all went up by 45 percent.”

For now, the home-run spike may even be helping the game. As Manfred has noted, the home run is one of baseball’s more popular plays; unsurprisingly, viewership is up since the power surge began. Though the accompanying rise in strikeouts may eventually dampen the enthusiasm, for now, casual viewers get a more entertaining product, while diehard fans get the satisfaction of believing they’ve solved the mystery MLB can’t crack.

Players could theoretically start the outcry. The Houston Astros pitcher Justin Verlander recently weighed in on Twitter, saying, “I don’t care if balls are juiced (seriously). We’re all using the same ball so it’s a fair field. My issue is I don’t like being lied to. I knew something was different. Century-old records are being broken and numbers are skewed.” But it’s unclear whether they have any leverage. MLB’s current collective-bargaining agreement, or CBA, provides for negotiation between the players union and the league over changes to the game’s rules or regulation. But without concrete evidence showing who is behind the alleged change, it’s hard to say whether the provision applies. Players could raise the issue in the next round of collective bargaining when the CBA lapses in 2021, but by then, the union will likely have bigger fish to fry.

The result is a situation tailor-made to stay unsolved. The source of the supposed juiced ball remains a mystery, and, with TV ratings up, the league may be less inclined to play detective. Still, Arthur said, “this story is not just going to die out. There’s further research in progress from some journalists and scientists, so there will be more coming out about how the baseballs are different.”

Lindbergh takes a longer view on the controversy’s future. “I tend to downplay the existential threat of these sort of things,” he said. “Baseball is always in flux, as the world is, and we’re constantly fretting about the latest crisis. You can go back in baseball history and every generation of fans and writers is worrying and complaining about the same subjects over and over again.”

That next change may have already begun. Through one month of the 2018 season, home-run rates are down slightly from the 2017 peak (although Arthur cautioned that unseasonably cold weather may explain the decline). This, Lindbergh said, is how these things typically go: “Baseball changed in some way, now we have all these homers. At some point, something else will change, and maybe we won’t have any homers, and we’ll all just move on with our lives and obsess with the latest way in which baseball is different.”

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