I think most people, including academics, lose sight of the fact that a market is made of people, not cards. There are no stationary stochastic processes that can be milked ad infinitum, markets are not some machine in an equilibrium that can be figured out. For the sake of argument assume there was some stationary edge, then somebody will figure it it out and eventually trade it with great size. That process guarantees most such 'edges' will vary with time.