The United States Bowling Congress has modified its rules on bowling ball gripping holes so that bowlers who don’t use their thumb during a delivery cannot have both a “thumb” hole and a balance hole. The move aims “to add greater clarity and fairness to ball specifications related to bowlers not using their thumb while delivering the ball,” USBC said in this news release. Under the new rule, any "thumb" hole that is not used for gripping purposes during the...