It is very easy to teach it. This is coming from what we did with mickey and from richling's book:
when you teach the dog you place them for the first week. NO CORRECTIONS. The next week you incorporate corrections. the week after that you teach stay by giving them the command and them holding the into position with one had on the chest and one near the shoulders. the next week you incorporate corrections on a stay and also go to the end of the leash. make sure to add plenty of distractions to your training. and only work the dog 6 days a week.
that is in the basic obedience training. remember these are intermediate dogs. They have been through long line work. Mickey is in the beg. of intermediate training, she is off the long line, but is not on a tab yet. she has I have just started sly on a tab. all the dogs are exceling. they are doing really good. its all about balance, but taking it one step at a time.
believe in your dog that he can do it. don't take your dog for granted.