Although four key executives have left Procter & Gamble during the past few months, CEO Bob McDonald isn’t losing any sleep over it. The four departing P&Gers are: Rob Steele, who will step down as head of healthcare in September to seek a chief executive role elsewhere; Ed Shirley, who will retire as head of beauty and grooming at the end of the year and has no immediate plans; Chip Bergh, who will become chief executive of Levi Strauss in September and Craig Bahner, who step...