More on what makes a BC a BC:
From way out in the field, the sheep are brought to the handler and penned in a small enclosure. The handler is not allowed to let go of the rope that is attached to the pen gate. He and his dog have to convince the sheep to go in without touching them.
The last exercise in the BC course. The handler stands in a ring with the sheep and the dog keeps the sheep there while the handler sorts off a specified number of sheep. Neither the handler nor the dog can touch the sheep and if the sheep leave the ring before the sort is done, they have to be re-gathered and it starts over.
A course the size of Edgeworth involves about twenty minutes of running and cantering and walking in a crouched position (oddly, almost never trotting as you'd see in the breed ring, which is supposedly the gold standard of athletic conformation). The dog must be incredibly in tune with the sheep, ready at a second's notice to anticipate and prevent any attempts to break off. This part is what the dog does naturally - we are not smart enough to be able to predict what a sheep will do like a predator can. Besides, look at how far that is - how can you see an ear twitch at that distance? BUT, the dog also has to be willing to take commands that don't make sense - a person may know ahead of time that bringing the sheep on the upper side of a rise rather than the lower, will prevent all kinds of problems. And something like splitting sheep up doesn't make any sense at all to a dog - he's been taught from a pup not to do that and now we're doing it on purpose! So the ideal dog also needs to trust people and be open to suggestions and naturally seeking to please.
Balance is the number one thing that is critical to a dog that works stock. The dog needs to have a ton of prey drive, but also has the ability to learn to control his impulses. This results in the kind of dog that can walk with the shepherd, relaxed, not bothering the animals he's passing - but able to spring into action and perform tasks as needed, as efficiently and gently as possible. Such dogs need tremendous work ethic and persistence to keep going when the job is incredibly difficult, but also the patience to wait when there's nothing to do. It's true that a BC left to its own devices will find a job to do, but a BC that knows his place in your household and has a routine, will have an "off" switch. I've had zillions of very high drive dogs come through here and have never failed to find and help the dogs use, their off switch.
Cesar Milan makes a big deal of walking his dogs off leash. It's an every day thing for a BC that's been raised right. A well bred, correctly raised dog (or trained) will think you are the most wonderful thing in the world and will have no reason to go anywhere. This picture is of a walk in an unfenced area, with a road, that went on for about three miles. We were just walking and talking, no one ever asked their dogs to stick around, they just did.