Of course Capel has a system. It's probably the same one Quin used at Mizzou (which we couldn't ever really figure out, either). It's basically the same philosophy that Duke employs under K. The problem is he's doing it with players typically much more skilled and almost always with a much higher basketball IQ. He can pretty much hand pick players he wants, so it works for him. His assistants/former players leave and try the same thing and realize it doesn't work so well without Duke talent.
If I remember Quin's explanations right, basically it's a system of no system. They're not going to run set plays, it's not really a true motion, but players are supposed to be able to read and react to every situation in a specific way. When it's done right, it works well. But when it's done with average to above average college basketball talent, it looks like five guys standing around the three point line then chucking up a bad shot.
Also... I find the "I don't care as long as we win" people a bit disingenuous. If you really don't care at all, why do you watch the game? All else being equal, EVERY basketball fan has a preferred style of play.