I'm not exactly sure what you're asking here, but there are many ways to get into the sports industry. Most GM's/assistant GM's are former players or coaches. I don't want to burst your bubble, but Its going to be almost impossible for you to reach this level. Realistically the number of people who aspire to be General Manager of professional sports teams far exceeds the number of GM jobs.
The best way to get a job as a GM would probably be to try and get a job as a scout and have a meteoric rise through the ranks as a talent evaluator. Baseball is also probably the best sport to try and break into. A few teams (Boston, Oakland, Toronto, Arizona etc.) are increasing relying on statistics over traditional methods to make talent evaluations and whose front offices have employees from many different backgrounds. I'm sure you've read moneyball. The Red Sox hired a poster, Eric Van, from the Sons of Sam Horn message board because he wrote so creativly and intelligent about the team.
Having said that sports teams have many employees in many different roles. Every team has a Public Relations, Marketing, Finance, Legal, and accounting department. Sports franchises give internships to undergrads which frequently lead to offers after graduation. A regular buissness degree (or even liberal arts degree) from a top school, will put you in better shape than a sports managment degree. Mark Cuban wrote about getting a job in sports in his blog once:
http://www.blogmaverick.com/entry/1234000963030046/
And the skills you get from earning an MBA will put you in great shape to land a more senior job with a team. Increasingly teams are owned by financiers and entrepuners who vaule the MBA skill set. Teams typically have Presidents who cordinate the talent evaluation and buissness side of sports franchises. Perhaps that something to aspire. Also more on the sports side of things, most teams employee several lawyers who specialize in player negotiations (and in the NFL most teams have salary cap experts).
And who knows? Theo Epstein worked as an intern for the Orioles, met Larry Luchino, got a job in public relations for the Padres, rose to the head of baseball development, followed Lucchino to the Red Sox and became the youngest GM in sports history. And Marty Hurney was a sportswriter before he became GM of the Carolina Panthers! Whatever career path you decide to pursue I wish you the best of luck.