KNOXVILLE -- John Jancek may feel good about just about every part of Tennessee's defense.
It's the one area of concern, though, that may cause the defensive coordinator the most consternation this month.
Heading into the season the Volunteers have yet to find who will fill the void left by A.J. Johnson and his 425 career tackles — the second-most in the history of the program — in what is easily the biggest question a promising defense must answer during its preseason preparations.
"It is totally wide open," Jancek said after the Vols finished Thursday night's practice indoors due to rain.
At this early stage of training camp, Kenny Bynum continues to get first-team work at middle linebacker, though the Vols coaches surely will rotate in the other candidates to see who can provide a calming influence in defensive communication and find the ball so consistently, as Johnson did during his four-year career.
Tennessee likes its young talent at linebacker, particularly with redshirt freshman Dillon Bates, freshman Darrin Kirkland Jr. and sophomore Jakob Johnson, who started two games at the end of the 2014 season when A.J. Johnson was suspended.
Walk-on Colton Jumper, a former Baylor School standout, redshirt freshman Gavin Bryant and freshman Austin Smith also could be factors as the Vols look for a player to match with Jalen Reeves-Maybin in its base defense and put between the junior and Curt Maggitt in a three-linebacker look.
"I'm looking for a leader," Jancek said. "I'm looking for someone that has great command on the field and great knowledge of our system and what it is we want to do. That's a position of concern, as you guys know. We have a great group there. They're competing extremely hard. We're just going to have to sort this thing out sooner rather than later.
"He is the quarterback of the defense," he added. "He sets the front. He gives all the directions with pressure and things of that nature. He's paramount in getting us lined up and getting us all on the same page.
"In order to do that, they have to great command, and they have to have a confidence. When they speak, the players have to have confidence in what it is they're saying and what they're hearing from him. He's clear; he's confident; he's loud. Those are the things that, I think, separate a lot of middle linebackers. It's not always just ability."
While it might make more sense for the Vols to use a bigger run-stopping linebacker to put in the middle against the run-heavy teams such as Arkansas, Georgia and Alabama this season and opt for a smaller, faster player against the spread offenses, Jancek made it clear he wants to find the answer in the middle and go with that player.
"I'd really like to go in with a clear-cut guy," he explained, "so there's confidence within the defense, there's been a cohesiveness and you're not bouncing guys in and out. Yeah, you're going to rotate players, but I want it to be solid. I guess that's the best word to describe it."
While Jancek may worry this month, Maggitt is confident the Vols will find a capable replacement.
"All those guys played with A.J. and they know it," he said after Tuesday's practice. "That linebacker room's got a culture, and when he left that culture's still there.
"Coach (Tommy) Thigpen does a great job, and he instilled that the Mike is the alpha male of the defense and he's got to be the one that's communicating and on point every play. I don't know, we've got some pretty good Mikes out there.
"With Bynum back there, I felt confident with him today. We did a good job, we had some really good communication and whoever Coach decides to put at Mike, we're going to trust in them and ball out."
Freshman defensive tackles Kahlil McKenzie and Shy Tuttle were impressive during a one-on-one pass-blocking period Thursday night. McKenzie bull-rushed his way into the backfield, bowling over guard Austin Sanders in the process. Tuttle drove Marcus Jackson, a fifth-year senior starter, into the backfield, then into the turf.
* Tennessee's "Circle of Life" made its debut Thursday night, with the 327-pound McKenzie and 350-pound guard Charles Mosley battling to a stalemate and quarterback-turned-receiver Jauan Jennings dominating his matchup with junior college transfer cornerback Justin Martin.
* Starting guard Jashon Robertson and defensive tackle Trevarris Saulsberry were held out of practice.
Contact Patrick Brown at firstname.lastname@example.org.