NPB's Double Motion Rule - The Evolution and Controversy of Pitching Form Regulations
NPB has long regulated pitching motions branded as 'double motion,' a topic of debate for over 30 years involving phases of stricter and looser enforcement. The rule aims to prevent unnatural deceptive deliveries but has wrestled with ambiguous adjudication and conflicts with international standards. The 2006 tightening and the 2011 liberalization marked major turning points. We trace the history of NPB pitching-motion regulation through controversy and globalization.