Highsmith, junior transfer from Phoenix College, wasn't prepared for the first-day assignment with the starting unit.
"The coaches told me there was an opportunity to play early and I liked that," Highsmith said. "But I didn't think they would put me with the ones on the first day. I thought I might have to work my way up."
Defensive coordinator Willy Robinson said it was a matter of trusting their recruiting instincts and Highsmith's instincts as a linebacker.
"He's done very well," Robinson said after Wednesday's two-hour workout. "He's still coming along. He stood out in our scrimmage (last week). He ran well. He tackled extremely well. We are still installing so there are new things being thrown at him every day, but he's learning well."
Highsmith thinks that is one of his strengths.
"I'm not perfect, but I am willing to learn," he said. "One of my beliefs and what I've been taught is that you need to learn one percent more each day. If you do that, at some point you will get there. So I'm trying to learn something new every time out.
"What I've seen is that at the Division I level, everyone is good and everyone is fast. I expected that. I think what I have going for me is the ability to learn at a fast pace. And I've been around football.
"I get football. There are different concepts to football, but a lot of it is the same. At the end of the day, it's still just football. They told me they had a need at linebacker and I knew I was a fast learner."
That doesn't mean anything is easy. Highsmith said there are no easy days going against an offense directed by Arkansas head coach Bobby Petrino.
"I've never seen anything like it," Highsmith said. "What I see is you are going against the best players anywhere. They have amazing athletes. These running backs and these receivers are all first rounders. That's what we measure ourselves against every day."
Defensive end Tenarius Wright sees the same thing. He said the defense is getting pushed to its limit in every situation.
"What we have on offense is great speed," he said. "And I'm impressed with the offensive line. I see an offensive line that can get to the next level of the defense because of its speed and defense. And I keep seeing more players stepping up. You could really see De'Anthony Curtis stepping up as a running back today."
Wright's words dripped with confidence in Petrino. Asked if he worried that Ryan Mallett's departure or any other developments would reduce the effectiveness of the offense, Wright had a quick conclusion.
"Not one bit," he said. "Coach Petrino always has a great game plan. He always is going to have an offense for the right situation. He's a guru. We are going to be in a position to be successful."
Robinson said he's pleased with the progress of the first team defense, but is still looking to secure more depth.
"Our first team defense was solid in the scrimmage," he said. "But we need depth in the front, linebacker and the secondary."
How about free safety where walkon Ryan Farr is working behind starter Tramain Thomas?
"Farr is the second guy right now," Robinson said. "We also are teaching free safety to Elton Ford and have worked Jerico Nelson at the (strong) safety. We want to know who our four guys are without trying to squeeze water out of a rock.
"Ryan still is learning to communicate. He tackled well in our scrimmage, but he's still not a consistent tackler. He's worked hard at it."
Robinson was asked about the progress of Darrell Smith and Daunte Carr at safety.
"Darrell is still handling some things in house," Robinson said. "He hasn't quite got it done. Carr is not 100 percent (healthy)."
Robinson praised his top cornerbacks, Isaac Madison and Darius Winston. He said Winston had a "great scrimmage. He was physical and right with everything."
The defensive players at the media session said they were looking forward to game time when they can unload on quarterbacks for the first time since last season. Robinson knows that's true.
"We saw how anxious they were in the scrimmage," he said. "I fully expect to see (in games) a talented team that can run and hit. We do try to take care of our teammates in practices. Coach (Petrino) has done a great job of picking and choosing when we do strike each other.