A National Leaguer is a professional baseball player who plays in the National League, one of two major leagues in Major League Baseball. The three solutions to the crossword are NAT, PADRE, and ASTRO, which refer to players from the National League. NAT is an abbreviation for the Washington Nationals, PADRE is an abbreviation for the San Diego Padres, and ASTRO is an abbreviation for the Houston Astros. STLOUISCARDINAL is an abbreviation for the St. Louis Cardinals, another team in the National League.