OKLAHOMA CITY (AP) Former Oklahoma football coach Barry Switzer admired one quality in Donnie Duncan above the many great ones his former assistant often displayed.

''He had great insight, a gift that a lot of people don't possess,'' Switzer said Sunday. ''The way he could articulate his thoughts and convey them to you was a gift. I told him I wished I had the ability to say and write like he did and put down his thoughts on paper - that's hard to do.''

Duncan, a former Oklahoma athletic director, Big 12 administrator and Iowa State football coach, died Saturday at the age of 75. Son-in-law Patrick Reardon said Duncan, who suffered from cancer, died in his sleep in Dallas.

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Duncan was on Switzer's staff from 1973-78, and he helped the Sooners go 62-6-2 during that span. Switzer said Duncan was an excellent recruiter who was great with players, and he regretted losing Duncan to the Cyclones.

''He was someone I relied on, who guided me when I was head coach and he was my assistant coach,'' Switzer said. ''I truly respected anything he had to give me.''

Switzer said Duncan had the personality to go with the intelligence.

''He had a great sense of humor,'' he said. ''He pulled some of the greatest practical jokes on our staff. He was a riot.''

Duncan's 1980 and 1981 Cyclone squads were ranked, and the 1981 Cyclones began 5-1-1 and were ranked as high as No. 11 in The Associated Press poll. Duncan's squads went 3-1 against Iowa, including three straight wins in 1980, 1981 and 1982. He went 18-24-2 in four seasons.

Duncan was executive director of the Sun Bowl and Gator Bowl before returning to Oklahoma, where he was athletic director from 1986 to 1996.

He was one of the Big 12's original staff members when the league began operations in 1996. He was senior associate commissioner and director of football operations for the Big 12 from 1996 until his retirement in 2010. Duncan was involved in every aspect of football in the conference, including officiating, bowls and television agreements. He was also responsible for developing the league's Football Championship Game and served as its director.

''The entire Big 12 Conference is saddened to hear of Donnie's passing,'' Commissioner Bob Bowlsby said in a statement. ''He was a great friend to all of us and one that we will miss dearly. Our condolences to his wife, Sally, and their entire family.''

Duncan served as chairman of the NCAA Special Events Committee, chairman of the NCAA Football Rules Committee and was a member of a special NCAA research committee that studied the possibilities of a football playoff. He also served on the College Football Association's television committee.

Switzer said he spent about 2 1/2 hours with Duncan a few weeks ago. Though Duncan was still mentally sharp, Switzer prepared himself for bad news.

''I knew it was coming,'' Switzer said. ''Donnie's been suffering for a long time.''

Reardon said Duncan was special as a family man, too.

''He was very much a father figure to me,'' Reardon said. ''I think we both came from similar backgrounds - really didn't have much growing up, and were kind of self-made people. He appreciated that in me and I in him. He was extremely strong, but loving and caring at the same time. He was a great role model for my children, and just a great guy, a fun guy to be around.''