Outspoken Bobby Valentine, who manages the Chiba Lotte Marines, promotes Japanese baseball internationally and encourages players not to defect to the U.S. major leagues in a new TV documentary that recently aired in the U.S.

Since 1995, when popular pitcher Hideo Nomo signed up with the Los Angeles Dodgers, 38 players have crossed the Pacific to don American uniforms for the world's best league, the film says.

Valentine fears the growing migration is depleting the sport in Japan of its luster, chipping away at its star power and adversely impacting its popularity, which has been on the decline.