 He then was out of baseball from 1979–87 before becoming a pitching coach at the minor league level in the Seattle Mariners' organization.He switched to the Montreal Expos' organization in the early 1990s, then to the Diamondbacks' farm system when that expansion team began play in , serving such teams as the Harrisburg Senators, Ottawa Lynx and Tucson Sidewinders.Kniffin succeeded Bob Welch as pitching coach of the defending 2001 World Series champion Diamondbacks in , when Arizona won 98 games and the National League West Division title before falling in the Division Series.