After his pitching career ended, Turner served the Yankees (1949–59; 1966–73) and Reds (1961–65) as their pitching coach, working for ten pennant-winning clubs over that 24-year span.
Turner was criticized by Jim Bouton in his book, Ball Four. Bouton claimed Turner (his pitching coach with the Yankees in 1966-1968) was a front-runner, who only wanted to be associated with successful pitchers. "In case you forgot," Bouton wrote, "you could always tell how you were doing by the way The Colonel [Turner] said good morning," citing that Turner would greet his stars effusively, middling pitchers brusquely, and with struggling pitchers he would "[look] past you, over your shoulder, as if you didn't exist." Bouton also criticized Turner for yelling obvious advice (such as "keep the ball down") from the dugout to a pitcher on the mound, as a preemptive second-guess. Bouton noted that pitchers know these principles already, and all the shouting can do is break their concentration. "But pitching coaches use shouted advice as protection. If they shout enough advice, they can't be wrong."