By Ryan AberStaff writer raber@oklahoman.comARLINGTON, Texas — Derek Green was a little unsure of what to do in mid-February. Green knew he wanted to leave Oklahoma after being on campus for just a few weeks after signing as part of the 2019 class. But making the decision where to go next was only part of his dilemma. Green, first, had to figure out how to get into the NCAA’s transfer portal. Since the database began during last season, “portal” has become the buzzword in college football. It was a big topic of conversation at not only last week’s Big 12 Media Days at AT&T Stadium, but at various media days around the country as coaches and players, still less than one year into the new landscape of being able to transfer without schools having the ability to block a player, still are navigating the system. In mid-July, a local university allowed The Oklahoman a brief look inside the portal.Read more on NewsOK.com