Herrmann developed a reputation as one of the best knuckleball catchers in the American League from his work with such knuckleball pitchers as Hoyt Wilhelm, Wilbur Wood and Eddie Fisher. Wood won twenty or more games for four consecutive years between 1971 and 1974 with Herrmann as his catcher. Unfortunately for Herrmann, trying to catch the unpredictable knuckleball pitch also contributed to his leading American League catchers four times in passed balls allowed. In , Herrmann was selected to be a member of the American League All-Star team.