BHP Billiton’s (NYSE:BHP) iron ore president Ian Ashby resigned from his position effective July 1st after being with his company for 25 years.His replacement will be Jimmy Wilson, a lead of the company’s energy coal division.BHP Billiton (NYSE:BHP) has potential upside of 23.3% based on a current price of $71.39 and an average consensus analyst price target of $88.BHP Billiton is currently below its 50-day moving average (MA) of $76.56 and below its 200-day MA of $78.45.