Sid Gillman was a great innovator who went 1-5 in postseason play.
Don Coryell was another innovator: 3-6 in the postseason.
George Allen went 2-7.
Bud Grant coached the Vikings to four Super Bowls, but lost all four and went 10-12 in the postseason.
Bill Cowher is apparently in demand as a coach but was only 12-9 in the postseason.
Dick Vermeil coached two Super Bowl teams and won one, but was only 6-5 overall in postseason play.