Wilcox says Lanier and Randolph have earned their snaps with quality work on the practice field.
"Izauea's been doing a good job," Wilcox said this week. "He's showed up more and more in practice, and that's where you earn your reps. You play well in practice and execute at a high level in practice to earn your reps, and he's done that."
Lanier spent the season's first three games backing up freshman Justin Coleman, who benefited from enrolling at mid-term and participating in spring practice. Now that Lanier has caught up mentally he has surged ahead on the depth chart.
"He's playing faster and more decisive," Wilcox said. "When he sees something he reacts quicker. When you play in this conference you can't be unsure. You've got to be decisive and go right now, and he's done that."
The coordinator also sees evidence that Randolph, listed No. 2 behind junior Prentiss Waggner at free safety, is on the verge of establishing himself as the nickel back.
"Brian has been doing a good job," Wilcox said. "He's very smart and he's a physical kid; he'll stick his face in there. He's gotten better with every rep. Brian has done a really good job of learning from mistakes. Whenever he sees it in practice, he can carry that over and not make that mistake again, which is obviously key to growth as a player."
As noted earlier, Coleman started the first three games at left cornerback. Another newcomer who already has made impact is defensive tackle Maurice Couch, a first-year juco transfer.
"Mo Couch has shown some things," Wilcox said, "but has got to be more consistent."
Several more first-year Vols are on the verge of becoming key contributors but the coordinator isn't ready to divulge any names beyond Lanier and Randolph just yet.
"Those are probably the two that have taken the biggest jump," Wilcox said. "That's to be expected here in the first few weeks just because of a little more experience for them."
Tennessee fans will be thrilled if Lanier and Randolph prove to be as productive in the secondary corps as fellow rookies Maggitt and Johnson have been in the linebacker corps. Maggitt recorded six tackles and a hurry in Game 3 at Florida, splitting time between strongside linebacker and rush end.
"Curt has done a really nice job of handling all of that," Wilcox said. "He's a bright kid. He cares about football. He studies it and wants to be good. That right there is what you want. He's not perfect by any means but there has never been a point where we felt like he can't handle it or he was overwhelmed."
Johnson, who posted seven tackles at Florida, also appears to be making remarkable progress for a freshman.
"A.J. is a guy we put a lot on," Wilcox said. "We haven't treated him like a freshman. Whether that's fair or not, that's just the way it is. A.J. is a big, physical guy. It hasn't been too big for him. He's made mistakes but he plays hard and he plays physical, and that's what we need."
Senior defensive tackle Malik Jackson is encouraged by the progress he sees from Tennessee's first-year defenders.
"I think they're coming along real good," he said. "At first, they were kind of scared and playing a little timid. As the season goes on and they have more and more practices, you see them running around full speed ... not thinking as much, just having fun.
"I see tremendous improvement in A.J. and Curt. I see them embracing their roles, listening to coaches and the older guys, then going out on Saturday and letting it loose."
Junior cornerback Marsalis Teague, who will start opposite Lanier on Saturday, also likes what he's seeing from the first-year defenders.
"Those guys are coming along real good," he said. "As they get more practice time and more game experience they can only get better. They've definitely got more knowledge and more confidence now."
Click play on the movie screen below to see more from Wilcox after Wednesday's practice at Haslam Field.