I saw a guy make this claim on FB but rather than shoot my mouth off as is my unfortunate habit, I did a little research first and darn, he was right. I found this link:
https://www.espn.com/chicago/nfl/story/ ... as-cowboys
and in it Dan Reeves is quoted as saying about Ditka:
People don't understand how extremely smart Mike is, just as far as his IQ. But his thought process coaching was [equally impressive]. Mike was the one who brought up the shotgun because we were so bad the year before on third-down conversions. ... Coach Landry had some experience with it and said he'd think about it, that we had to work on our pass protection because the first thing people would do is blitz us. But we used the shotgun a long time before anyone else did. ... Roger Staubach was awesome in the shotgun and that was something Mike brought up first.