In this groundbreaking book, Keith Law, baseball writer for The Athletic and author of the acclaimed Smart Baseball, offers an era-spanning dissection of some of the best and worst decisions in modern baseball, explaining what motivated them, what can be learned from them, and how their legacy has shaped the game. For years, Daniel Kahneman's iconic work of behavioral science Thinking Fast and Slow has been required reading in front offices across Major League Baseball. In this smart, incisive, and eye-opening book, Keith Law applies Kahneman's ideas about decision making to the game itself. Baseball is a sport of decisions. Some are so small and routine they become the building blocks of the game itself--what pitch to throw or when to swing away. Others are so huge they dictate the future of franchises--when to make a strategic trade for a chance to win now, or when to offer a millions and a multi-year contract for a twenty-eight-year-old star. These decisions have long shaped the behavior of players, managers, and entire franchises. But as those choices have become more complex and data-driven, knowing what's behind them has become key to understanding the sport. This fascinating, revelatory work explores as never before the essential question: What were they thinking? Combining behavioral science and interviews with executives, managers, and players, Keith Law analyzes baseball's biggest decision making successes and failures, looking at how gambles and calculated risks of all sizes and scales have shaped the sport, and how the game's ongoing data revolution is rewriting decades of accepted decision making. In the process, he explores questions that have long been debated, from whether throwing harder really increases a player's risk of serious injury to whether teams actually "overvalue" trade prospects. Bringing his analytical and combative style to some of baseball's longest running debates, Law deepens our knowledge of the sport in this entertaining work that is both fun and deeply informative.