Using his sinking palmball heavily, Giusti recorded 20 or more saves in each of the next four baseball seasons, and he led the National League with 30 saves in 1971 for the Pirates. Giusti appeared in three games for Pittsburgh in the 1971 World Series, earning a save in Game Four.
Giusti's exceptional performance as a relief pitcher was highlighted by his consistent ability to record 20 or more saves each season, culminating in him leading the National League with 30 saves in 1971 while playing for the Pirates. He also participated in three games during the World Series and secured a save in Game Four.