In the same way that 1968 is known as “The Year of the Pitcher,” 2019 will likely be remembered as “The Year of the Home Run.” A staggering number of records were broken, not the least of which was the single-season record. The 6,776 home runs hit this year surpassed the previous record — 6,105, set in 2017 — by 11 percent. By the end of the first week of April, Baseball Prospectus analyst Rob Arthur found that the 2019 ball had lower drag, a result that was corroborated by MLB officials. Players also said that the feel of the ball had changed dramatically. Over the course of the season, further research by Arthur, myself, and Barton L. Smith confirmed that the ball’s construction was indeed different and the decreased drag was likely due to lower seam height. After denials from MLB of any intentional change, discussion of the ball reached a fever pitch at the All-Star Game, when AL starting pitcher Justin Verlander opined that MLB had...