Nippon Professional Baseball switched to a uniform baseball in line with Japanese pro baseball specifications Tuesday following a controversy over baseballs that had been livelier than the permissible limit.
NPB officials were on hand at the six ballparks in the Central and Pacific leagues to verify delivery of the baseballs. There were a total of 10 home runs in five games the same day, the only exception being at Kobo Stadium in Sendai, where the Tohoku Rakuten Golden Eagles faced the Chiba Lotte Marines.
"We confirmed their operation. There was no difference (in appearance) from the balls being used up until now," said senior NPB official Minoru Hirata. A steady supply of baseballs was deemed possible last Friday after successful tests on a pre-shipment of newly manufactured baseballs.
NPB conducted unofficial tests on balls before the start of the season and said based on data acquired on March 19 that although the balls were within the permissible limit, their "coefficient of restitution" was close to the maximum limit.
In October last year, Ryozo Kato resigned as NPB commissioner to take the fall after the ball used last season had been secretly altered without his knowledge.