Two games into his career, Jefferson has looked like a veteran, sniffing out plays and closing quickly on wide receivers.
"I've always had closing speed even since Pop Warner," Jefferson said. "When I was young, I didn't know what closing speed meant ... It's just instinct."
Coaches like the current nickel platoon. Jefferson, though, is hungry to add more. He's a film junkie who studies Ibiloye's role when he's on the sideline.
"By no means has he arrived," said defensive backs coach Willie Martinez. "He's still learning our defense. We're giving him a little bit more each game ... But he has that 'it' factor coaches like to say a lot of times, the instincts, an understanding of the game."
Jefferson's role long-term is yet to be determined. And comparisons between newcomers and past greats are often unfair, whether it's Landry Jones to Sam Bradford or Jefferson to Williams.
"I do know he's from California," Jefferson said. "That's a big key right there. And I do know he came and brought the wood when it's time to hit. I know he could cover. That's what made him such a valuable player."
But if it wasn't for Clay's recruiting pitch, Jefferson might be playing on the West Coast.
"Brennan was committed forever," Jefferson said. "He was always in our ear, saying, 'You should give Oklahoma a try.' He said, 'Come out here and see what it's about.' At first I wasn't really listening to him. I was USC, then Cal. But I decided to weigh all my options."
Jefferson eventually called Bobby Jack Wright to set up a recruiting visit to watch the Sooners play Kansas State on Halloween.
"I really didn't know much about them," Jefferson said. "I ended up really liking it, the tradition, the atmosphere, the players. It all fell into place ... I love it here."
High School: Eastlake
Hometown: Chula Vista, Calif.
Noteworthy: Selected to participate in the U.S. Army All-American game, the four-star recruit recorded 88 tackles and four sacks in 2008... Graduated early to participate in OU's spring practice.
Jefferson on his nickname "El Tigre.": "A friend back home (gave it to me). Of course, Tony the Tiger. Frosted Flakes. I don't know how that got back here. I think either Kenny (Stills) or Brennan (Clay) put that up and the team has been calling me that. I actually eat Frosted Flakes. But I didn't when I was younger because I choked on a flake so my mom didn't let me eat them. I had to grow into that."