 Originally signed by the New York Yankees as an amateur free agent in , Santana spent several years in their farm system before being traded to the St. Louis Cardinals on February 16, for a player to be named later.The Cardinals sent pitcher George Frazier to the Yankees in June to complete the deal.Santana made the Cardinals out of spring training in , making his major league debut on April 5 at third base in the season opener against the Pittsburgh Pirates.