What I am suggesting to you though, which my friend never totally achieved, jsut partial, is that if you can find 18y/os that turnaround that well, you can find more well rounded older and middle aged guys.
Oh, yeah, I've had to do that at the other positions, but usually with the older guys. Except that instead of flipping, I generally am trying to find guys with specific skill profiles who are also American, and at a reasonable rate so I can continue putting most of my money into the arena.
As far as flipping youngsters quickly, one would assume that would actually work better by two position training, since the training is definitely more than 60% of single position, and it's much easier to guarantee 5 guys 48+ minutes than to get 3 guys 48+. I've just always looked at it as being cheaper to buy a guy and make him into the skill profile I want than it would be to find a guy who's already there and pay someone else a similar or even higher every week until that time comes. I suppose if I were one of those insane JS trainers, there's probably a glut of those guys that can be picked up cheaply enough to make it pointless. ;)