Wilhelm was noted during this period for his mentoring of relief pitcher Wilbur Wood, who came to the 1967 White Sox in a trade. Wood sometimes threw a knuckleball upon his arrival in Chicago, but Wilhelm encouraged him to throw it full-time. By 1968, Wood won 13 games, saved 16 games and earned a 1.87 ERA. He credited Wilhelm with helping him to master the knuckleball, as the White Sox coaches did not know much about how to throw it. Between 1968 and 1970, Wood pitched in more games (241) than any other pitcher and more innings () than any other relief pitcher.