We are in a historic era for the home run, resulting in more strikeouts, longer games, and what feels like the logical conclusion of the analytics era. Wall Street Journal national baseball writer Jared Diamond reveals that the secret behind this shift isn't steroids or the stitching of the baseballs, it's the most elemental explanation of all: the swing. Diamond tracks a group of baseball's biggest stars—including Aaron Judge, J.D. Martinez, and Justin Turner—who remade their swings under the tutelage of renegade coaches whose ranks include a swimming pool contractor, the owner of a billiards hall, and an ex-hippie inspired by surfing and the technique of Japanese samurai.