Robert Calvin Hubbard (October 31, 1900 – October 17, 1977) was an American professional football player and Major League Baseball (MLB) umpire. After playing college football at Centenary College and Geneva College, Hubbard played in the National Football League (NFL) between 1927 and 1936 for the New York Giants, Green Bay Packers and Pittsburgh Pirates, playing the bulk of his career with the Packers. Hubbard is credited as being one of the inventors of the football position of linebacker. He was also an umpire in the American League (AL) from 1936 to 1951, then worked as an umpire supervisor until 1969. George Halas affectionately called Hubbard the "Big Umpire." To date, Hubbard is the only person to be enshrined in both the Pro Football Hall of Fame and Baseball Hall of Fame. He is also a member of the College Football Hall of Fame. Early life Cal Hubbard was born in Keytesville, Missouri to parents Robert P. and Sarah "Sallie" (Ford) Hubbard. He grew up in modest means as the son of a small family farmer. Cal graduated from Keytesville High School, but because the school had no football team he also attended one year at Glasgow High School in nearby Glasgow, which did offer football. Already tall and weighing 200 pounds as a 14-year-old, Hubbard displayed natural athletic gifts. He aspired to attend the United States Military Academy at West Point, New York; however a physical discovered he had flat feet, eliminating him from eligibility. From an early age Hubbard was involved with sports. He umpired pickup baseball games at the age of 18. Hubbard chose to attend a college or university that offered football, selecting Chillicothe Business College in Chillicothe, Missouri while also continuing to work around his family farm. A chance meeting in 1922 with Bo McMillin, the new football coach at Centenary College in Shreveport, Louisiana, led Hubbard to enroll and play football there from 1922 to 1924. Hubbard was the school's first All-American. Georgia Tech coach Bill Alexander once watched Centenary when it was in town to play Oglethorpe. "Bo, this Oglethorpe bunch has fast backs, but the line is light and green. If you turn that Hubbard loose, he might kill some of them. Have Cal 'hurt his knee', why don't you, and let him sit on the bench?" When McMillin moved on to suburban Pittsburgh's Geneva College, Hubbard followed him and played there