Normally GP in any scorebook stands for Games Played.
major league baseball
Extra Hitter. Player hits in batting order but is not in the field.
national league baseball
On Base Percentage
GBL in Baseball means "Golden Baseball League
MLB may stand for several different things. It is most commonly understood to stand for "Major League Baseball", a baseball organization popular in the United States. In business and accounting it stands for "Material, Labor, Burden."
Major League Baseball Players Association
Performance enhancing drugs
A "score" is 10 years. (:
NBL stands for NationalBasketball Baseball League Basketball is the NBA National Basketball Association