Valentine was widely recruited out of Rippowam High School in Stamford, Connecticut as a star in American football and baseball. He was recruited by the likes of the University of Nebraska, Duke University, the University of Notre Dame and the University of Southern California. He attended USC where he became a member of Sigma Chi Fraternity and Arizona State University. He was then drafted and signed by the Los Angeles Dodgers in 1969. He is considered to be among the best high school athletes in Connecticut history.