Jack is a native of Southern California. He was drafted by the Boston Red Sox in the 20th round of the 1984 MLB draft but did not sign, choosing to attend Stanford University instead. At Stanford he was the co-Freshman of the Year in 1985, a 2nd team All-American in 1986 and a 3rd team All-American in 1987. He led Stanford to the 1987 College World Series championship.
Jack was drafted again, this time in the 1st round (5th pick) of the 1987 MLB draft by the Chicago White Sox. After just 6 games in the Minor Leagues, Jack made his Major League debut. He played for 12 years in the Major League, with the White Sox, New York Yankees, Cleveland Indians and Anaheim Angels. "Black Jack", as he is nicknamed, was a three time All-Star and won the American League Cy Young Award in 1993. During his MLB career Jack compiled a 127-87 win-loss record with a 3.85 ERA.
In 2014, Jack was hired by the Los Angeles Dodgers to manage in their minor league system for their Ogden Raptors (Rookie League), and then in 2015 he was named manager of the Arizona League Dodgers. Prior to this, for 7 years he coached high school baseball at San Dieguito Academy in Encinitas, CA.
Off the field, Jack has also been a professional musician, with the rock bands V.I.E.W. and stickfigure.
Jack is married to his wife, Kerrie, and is father to his three sons Lucas, Rhett and Rory. and to his daughter Molly.