New York Yankees pitcher, Mariano Rivera, retired at the end of this baseball season. After all the years Rivera he’s spent in the league—he’s retiring at age 43—it’s easy to forget where he came from. But I won’t make you look it up. Rivera is a product of the New York Yankees farm system. (If you’re not a baseball fan, the farm system is a network of minor league teams that supports the major league teams—it’s where talent is developed).