We are in a historic era for the home run. In 2019, MLB saw the most home runs ever in a single season- 6,776, to be exact-obliterating a record set just two years before. Each of the last four years ranks among the top five most home run-friendly seasons in baseball's 150-year history, far surpassing even the totals of the Steroid Era of the late 1990s. This home run boom has transformed the game, contributing to more strikeouts, longer games, and what feels like the logical conclusion of the analytics era. SWING KINGS: The Inside Story of Baseball's Home Run Revolution (William Morrow; Trade Paperback; 9780062872111; on sale March 23, 2021) by Jared Diamond, the Wall Street Journal's national baseball writer, tells the story of this remarkable shift.

In a fascinating, character-driven account, Diamond reveals that the primary driving force behind this unprecedented home run phenomenon isn't steroids or the stitching on the ball, but rather the most elemental explanation of all: the swing. Diamond follows four of baseball's biggest names who remade their swings and soon saw their stats soar: Aaron Judge of the New York Yankees, J.D. Martinez of the Boston Red Sox, Justin Turner of the Los Angeles Dodgers, and Josh Donaldson of the Minnesota Twins. As skilled as these players are, to think they perfected their swing on their own would ignore the real heroes behind this home run revolution: their coaches. But not the hitting coaches employed by their teams- rather, an unusual group of baseball washouts and oddballs who preached a new way to swing, one that ran counter to generations of hitting instruction.

For years one of the game's best-kept secrets, these coaches are now moving from baseball's margins to its center of power and changing the way hitting is taught to players of all ages. SWING KINGS tells the story of Craig Wallenbrock, the movement's seminal figure, who draws his inspiration for the baseball swing from surfing and Japanese samurai. It follows Bobby Tewksbary, who never quite made it as a player, but reached the game's pinnacle as a hitting coach, only to watch it all fall apart. And then there's Richard Schenck, a middle-aged dad with no serious baseball qualifications, who went from tinkering in his basement to reshaping Aaron Judge's swing.

Through Diamond's masterful storytelling, this wild cast of characters comes alive. And Diamond, whose own baseball career ended in high school, also trains with them himself. Taking a page out of the George Plimpton playbook, he enlists their tutelage with an eye toward starring in the "World Series of Journalism," the annual Boston - New York media game at Yankee Stadium. In the process, he answers the ultimate armchair slugger's question of nature vs. nurture: "I may not be as strong or as coordinated as the pros, but if I had cutting edge instruction, and worked at my game, how good could I be?"

For fans of the game, old and young, in SWING KINGS, Diamond turns an elemental facet of baseball into a page-turning narrative exploration of our nation's pastime at a crossroads. At the same time, he explores the science, technology, and shifting strategies and economics that are changing the way the game is played.