Launch fly balls for better batting statistics: Applicability of “fly-ball revolution” to Japan’s professional baseball league

ABSTRACT “Fly-ball revolution” in Major League Baseball (MLB), spotlighting an underlining tenet that batters should aim for big fly balls rather than grounders, has attracted interest from countless players around the world. Its applicability, however, is not clear for players of different physical abilities or teams with different game strategies from MLB’s. This paper aims to test a hypothesis that hitting fly balls do not result in better batting statistics than hitting grounders in Japan’s Nippon Professional Baseball (NPB). From radar-tracking outputs collected in the official games, the speed, launch angle, and batting results of all batted balls in play were extracted (n = 39,469). In-play batting average (IPBA) and slugging percentage (IPSP) were compared between fly balls and grounders. The results showed the better batting statistics for fly balls (IPBA = 0.381 ± 0.018; IPSP = 0.730 ± 0.079) than grounders (IPBA = 0.267 ± 0.010; IPSP = 0.285 ± 0.010). Thus, our hypothesis was rejected. The balls launched at 10°−20°, called line drives, resulted in higher IPBA over the typical speed range (120 − 150 km/h), suggesting that NPB players whose ball speed was typical should aim for line drives, rather than high fly balls by accepting the tenet.