I think some of the initial responses were pretty accurate. Schutzhund training is not quite the same as "guard dog" or "protection dog" training, and although there are some sport trained dogs who make very effective real-life protection dogs without requiring more specialized training, there are also some that will not.
I heard someone describe to a novice once that schutzhund is a sport like boxing, and the dogs are atheletes like professional boxers. There are some individuals who are very good technical boxers who wouldn't employ those skills outside of the ring. There are others (he used the example of Mike Tyson) who are good in the ring, but, if you wanted to confront them in a street fight, with no boxing gloves on, they will accept your challenge on those terms as well. I think it's a good analogy to schutzhund dogs, because they are all individuals, and just as some of our dogs have no problem applying their training to "real life", other dogs view schutzhund protection as merely a game. In short, it isn't fair to expect a dog to confront what is supposed to be a real world threat simply on the merit of it being a schutzhund trained dog.