In the NFL, it's Al Davis in the Super Bowl Era who for four decades (1972-2011) was the owner+GM of the Raiders.
In MLB, it was the Yankees' owners George Steinbrenner comes to mind as an intervening owner in the 1970's ...but he had a solid background in sports (assistant coach in college, running a pro basketball franchise in a rival league to the NBA).
Just to tag on. Davis was a coach at the college and professional level fifteen years. Served as the old AFL commissioner for a year.
Steinbrenner and Davis were not perfect. Steinbrenner was bombastic with his team and the media during the 1970s and 1980s. The NFL began to evolve beyond Davis' 'Just Win Baby' football philosophy by the mid-1980s.
That said, as you are pointing out, both had gained experience and met any reasonable minimal professional requirements for running a professional sports team operations years before having the opportunity.
There is a contrast between these individuals, whom some people repeatedly and incorrectly claim are equivalents in sports team management, and Jerry Jones. Jones played college football. He tried his hand at the pizza restaurant and insurance industries. He was pulling crude from beneath the ground when he saved enough money and borrowed the rest to buy the Dallas Cowboys franchise.
That is a summation of his pre-ownership/general manager experience prior to February 1989. He has been trial-and-erroring ever since. His fellow Arkansas Razorback alum first born was a chemical engineer prior to dad buying the franchise. He has been stumbling since day one too--although, he can promote the hell out of a rodeo.
Fate can be a cruel mistress. Some Cowboys fans understand this most of all.
