1. Regression to the mean. Apple came up with the iPod in 2001, the iPhone in 2007 and the iPad in 2010, in each case not only creating a blockbuster new product but a whole new category. Like a football quarterback who throws for 400 yards a game for a month, Apple is overdue for a slump. "Apple was essentially in violation of business physics for an extremely long time," says Harvard management professor Gautam Mukunda in the book. Today, portable music players are an aging product category and competitors are stealing market share from the phone and tablets. Will Apple be able to pull another rabbit out of its hat?