This is from his Wiki:
Brandt served as the Cowboys' chief talent scout since the club's birth in 1960. He had served as a part-time scout for the Los Angeles Rams under General Manager Tex Schramm in the 1950s. When Schramm took command of the newly formed Dallas franchise in 1960, Brandt was one of the first people he hired. Schramm, Brandt and Coach Tom Landry formed the triumverate which guided the Cowboys for their first 29 years.
Brandt helped pioneer many of the scouting techniques used by NFL clubs today, such as computer analysis of prospects (especially those from small colleges), converting basketball players and track athletes into football players and finding top free agent rookies, such as Drew Pearson, Cliff Harris, and Everson Walls. Brandt was also one of the first NFL talent scouts to look outside the United States for potential players. For example, he looked to Latin American soccer leagues for kickers.
I think one of the things Brandt brought to scouting was science like measuring different athletic attributes and I think he was one of the founders of the 40 yard dash.
Others who are older than me and know the history better than me might be able to shed more light on this but he was a visionary. He was one of the main brains that allowed the Cowboys acquire the talent to pull of 20 straight winning seasons. In that whole time they only had one franchise QB and they only got him after 5 years in the armed forces and the rust that it entailed.