Technical Indicators - Playing the Bands

Playing the bands is based on the premise that the vast majority of all closing prices should be between the Bollinger Bands. That stated, then a stock's price going outside the Bollinger Bands, which occurs very rarely, should not last and should "revert back to the mean", which generally means the 20-period simple moving average. A version of this strategy is discussed in the book Trade Like a Hedge Fund by James Altucher.