Report: Baseballs used since 2015 are bouncier, lighter, less air-resistant

Studies performed at the Keck School of Medicine and the University of Southern California revealed that, since 2015, the chemical properties and density of baseballs have been altered, according to FiveThirtyEight.

Research shows the cores of baseballs used since the 2015 All-Star game weigh half a gram less than before, which, per the study, could send a new ball hit on a home run trajectory approximately six inches further.

Baseballs are also lighter and bouncier, which would add close to 0.6 mph off the bat, according to analysis conducted by The Ringer's Ben Lindbergh in June.

Skepticism over modifications made to baseballs has coincided with a historical increase in home runs. In 2017, players combined to hit a record-breaking 6,105 home runs and 1.26 per game, blowing past the 5,693 set in the steroid era of 2000. The World Series, featuring the Los Angeles Dodgers and Houston Astros finished with 24 home runs hit across seven games. Game 2 alone saw a total of eight home runs, the most ever in a World Series game.

Commissioner Rob Manfred has repeatedly denied allegations suggesting a change to the baseballs is behind the game's home run surge.