 Immediately upon graduation, Arnsparger was hired as an assistant coach with the Miami football program, beginning a long career in the profession.Arnsparger is best known for serving as a defensive coordinator in the National Football League (NFL) for Miami Dolphins teams that won consecutive Super Bowls (1972 and 1973) and reached another (1982), all under head coach Don Shula.Arnsparger's defenses were an important part of the Dolphins' success, and earned two nicknames over his tenure – the "No-Name-Defense" in the 1970s and the "Killer B's" in the 1980s.