Robertson broke into the Pirates’ regular lineup in , playing alongside future Hall-of-Famers Roberto Clemente and Willie Stargell. On August 1 of that year, at Atlanta–Fulton County Stadium, Robertson and Stargell each collected five hits in a 20-10 victory over the Atlanta Braves. Not until Andrew McCutchen and Garrett Jones in would Pirate teammates again collect five hits in the same game. That season, Robertson batted .287 with 27 home runs and 82 runs batted in (all career highs) on a team that won the National League East Division, the Pirates' first trip to the post-season since winning the 1960 World Series. However, they were defeated in the National League Championship Series by the Cincinnati Reds.