Whereas Stocker did everything reasonably well, his successors at the position are a bunch of guys who do one thing well and several things not so well.
"Right now we're kind of a bunch of missing pieces, trying to get a guy with all of that skill set that Luke's got and the confidence Luke had," Russell said. "We've got some guys that just aren't sure of themselves right now, and that's where I've got to do a better job of coaching 'em, making sure they understand how to go about becoming a good player and making 'em understand what their role is."
The heir-apparent to Stocker is Mychal Rivera, who caught 11 passes for 112 yards as a sophomore backup last fall. At 6-3 and 262 pounds, Rivera is three inches shorter and nine pounds heavier than Stocker. His stockier build helps in the run game but his inexperience hurts in every other area. Whereas Stocker was a fifth-year senior last fall, Rivera will be a second-year junior college transfer next fall. As a result, he is nowhere near as comfortable with the scheme as his predecessor.
"It's just the progression of taking that next step and understanding the whole big picture," Russell said. "I think Mike's got a little bit better idea. Last year he had no idea what was going on around him and why his route had to be this way or blocking fundamentally in technique."
Still, Rivera had a pretty good first scrimmage on Saturday, catching three passes for 23 yards.
"Bart's actually been training some at the F, the fullback spot," Russell said. "He'll probably start making the transition back to some on-the-line stuff later in the spring but he's been with Chino (running backs coach Chino Fontenette) more this spring than with me."
"He does pass the eye test," Russell conceded, "and his measurables - his 40 time, his agility and his vertical leap - he's got all of that. Brent's just got to pour himself into our playbook and learn the position because he does have a good skill set. Right now it's the total understanding of things and some fundamentals (that holds him back)."
Mid-term freshman Brendan Downs has a lot of potential in the passing game. He caught two passes in Saturday's initial scrimmage but, at 6-6 and 230 pounds, may need more bulk in order to contribute significantly as a blocker in the ground attack.
"He runs well, he's physical and he's a bright kid," Russell said. "He's going to be fine."
Tennessee's most gifted tight end may not be on campus yet. Cameron Clear, a 4-star recruit from Memphis, has the size (6-6, 265) and athleticism to make an immediate impact if he can learn the position quickly. Tight end is not the easiest spot for a freshman to pick up in Tennessee's system, however.
"It depends on what we're going to ask him to do," Russell said. "If we control what he has to know, you can get a young guy ready. We can't expect him to come out and be Luke.
"You're going to have to hope a guy has some natural football instincts and gets to spend all summer here, then learn to get out there and compete. It's hard, though, especially in this offense with what we'd love for our tight end to be."