Who are the greatest pitchers in the history of baseball? Who are the greatest pitchers pitching today? What makes a pitcher great? From the heroes of yesterday like Cy Young to modern superstars like Mariano Rivera, author Ken Rappoport looks at ten of the greatest ballplayers (Grover Cleveland Alexander, Lefty Grove, Walter Johnson, Sandy Koufax, Christy Mathewson, Satchel Paige, Mariano Rivera, Nolan Ryan, Warren Spahn, Cy Young) to ever stand atop a major-league pitcher's mound.