USBC on Thursday finally announced its new rules for urethane (aka slow oil-absorbing high-performance) bowling balls that will take effect Jan. 1, and they are a significant step after years of the sport's national governing body failing to govern urethanes. They include a sometimes puzzling mix of complete bans on urethanes, allowing urethanes made at 78D or higher, and no changes — depending on the competition.   By not enacting a urethane ban for all national competitions and...