Montague also umpired in seven League Championship Series (1979, 1987, 1992, 1996, 1999, 2001, 2002), and in seven Division Series (1981, 1995, 2000, 2003, 2004, 2005, 2007). He was the first base umpire for the single-game playoff to decide the NL's 2007 wild card team. He became an NL crew chief in 1996 after the death of longtime umpire John McSherry on Opening Day at Riverfront Stadium in Cincinnati.