This is not how anyone thought things would look when the Boston Red Sox rolled into the Bronx to face the New York Yankees for the first time in 2021. The Red Sox, who appeared to be in at least a partial rebuild, have spent much of the season atop the AL East and now sit in second, four-and-a-half games ahead of the all-in Yankees.
More surprising still is how the Yankees have landed in fourth place in early June. The Bronx Bombers were mostly expected to live up to their name — carrying what looked like a world-beating lineup into the season with a risky, unsteady pitching staff outside of Gerrit Cole. The reality has been anything but. Their vaunted offense ranks 22nd in OPS, 15th in park-adjusted wRC+ and first in puzzled scrutiny entering Friday’s series opener.
BetMGM has the total set at 9.5 for Sunday night, but it’s not safe to assume these two historically powerful lineups will engage in slugfests.
New York’s persistent impotence has baffled oddsmakers. Yankees games have come in, on average, a full run under the Las Vegas total line in 2021 — the most extreme low of any team — and only Washington Nationals games have hit the under more often than Yankees games (62.5 percent).
And while they have suffered from injuries, some openly bad play and probably some bad luck, the lower scores may also be a function of something totally outside the players’ control, baked in to Yankee Stadium and the baseballs in play there.
A deadened baseball and the Bronx bandbox
MLB is trying out some slightly deadened baseballs in 2021, or attempting to. According to a memo widely reported this spring, the league instructed Rawlings to make balls for 2021 slightly less bouncy. The loosening of a wool layer also made the new version of the ball slightly lighter.
Hitters have feasted at Yankee Stadium during the home run surge that MLB’s ball modification is meant to counteract.
From 2016 through 2020, balls leaving the bat at 95+ mph with a launch angle between 15 and 35 degrees — which we will call homer-quality contact — produced a 2.018 slugging percentage at Yankee Stadium, sixth-highest of any venue in the league. And 38 percent of those balls went for home runs, tied for the second-highest rate in baseball.
In 2021, overall home run numbers are down because hitters are just making less contact. But even when they are connecting, batters are finding less success on the other end of a well-struck ball. The batters at Yankee Stadium, no matter which side they’re playing for, are suffering more than most.
The Yankees themselves had the league’s second-best home slugging percentage between 2016 and 2020. In 2021 so far, they’re languishing in 26th.
After years of being one of the most advantageous places to hit the ball hard in the air, Yankee Stadium has the fourth-lowest batting average and sixth-lowest slugging percentage on homer-quality contact in 2021.
It’s keeping company with parks, including Citi Field just across town, that have added Humidors over the past two years. The Yankees have not added one, though, and a spokesperson said they have not made any alterations to how they store baseballs in recent years.
Beyond the leaguewide ball-related offense decline, there might be a more gradual combination of reasons for the seemingly sudden downturn in Bronx bombing.
It’s notable that Yankee Stadium’s home run rate on good contact isn’t down much. But the balls that stay in the yard are less productive, and that likely has to do with defensive positioning. As the prominent analyst Rob Arthur has pointed out at Baseball Prospectus, teams have moved their outfielders back in recent seasons and wiped out a significant number of hits. That effect could be magnified in a park like Yankee Stadium with relatively little outfield ground to cover in the first place.
So here’s the park’s reputation acting as double-edged sword. A greater portion of batted balls are being hit at that homer-quality contact, but fewer of them are turning into homers or even hits.
Is Yankee Stadium a pitcher’s park now?
One thing we know for sure is that baseballs fly more freely in warmer weather, so you should always expect home runs to pick up in the summer months — especially in more starkly seasonal locales like New York. But Yankee Stadium’s homer rate on homer-quality contact is still lower than it’s ever been during the homer surge, even when you limit prior years to games before June 1.
Dr. Meredith Wills, an astrophysicist who has researched the composition of the baseball over the past five years, said during a SportTechie panel this week that her early looks at 2021 baseballs have led her to the hypothesis that humidity changes could have greater effects than on previous versions of the ball.
So yes, it could be a simple matter of Bronx weather or wind conditions breaking exactly the wrong way for hitters. (Citi Field is also playing as an extremely pitcher-friendly park in 2021, but that is not out of the ordinary.) However, if the changes to the baseball altered its reaction to the air, its future behavior may also buck our expectations.
The question, then, is whether these dynamics will last. And the answer is that we don’t know. For now, it’s more likely that the Yankees will remain caught up in the offensive malaise gripping the sport.
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