As MIT Sloan Sports Analytics Conference kicks off, scholars and fans have produced a growing avalanche of quantitative research. Imagine if your hobby became your profession — or, indeed, if it started a whole new profession.This year, the MIT Sloan Sports Analytics Conference features someone who can make that claim: Bill James, the baseball analyst whose pioneering work opened up the entire field. On Friday and Saturday, James will speak for the first time at the MIT conference, the biggest event of its kind.A high school English teacher and factory watchman from Kansas, in 1977 James began self-publishing an annual baseball book analyzing how well the sport’s conventional wisdom held up to hard statistical evidence. By 1982, “The Bill James…