When current Red Sox manager John Farrell took over as pitching coach in 2007, he inherited a starting rotation that had a 5.00 ERA (ranked 24th) the year before and helped guide it to a 4.21 ERA (fourth) and a World Series title in his first year. Before Farrell, the Red Sox had used six pitching coaches in five years. Farrell is the only person to keep the job at least three full seasons since Bill Fischer did it from 1985 through 1989.
JUAN NIEVES: Start of 2013 to May 7, 2015
Age at hire: 47
Personal career: 32-25, 4.