While there’s optimism that Tennessee will see an offensive resurgence under its latest regime change, the early returns of the Josh Heupel era might be actually determined by just how often the Vols can keep opponents out of the end zone.

Under Heupel, Tennessee is going to find ways to manufacture points. But can the Vols avoid seeing the scoreboard constantly flash for the opposition?

The Vols were middling on defense in 2020 — ranking 76th nationally in yards per play (5.83) and 69th in scoring allowed (30.1 points per game) — and that was with the services of guru coaches Jeremy Pruitt and Derrick Ansley plus top tackler Henry To’o To’o.

Obviously, Pruitt and Ansley are gone, and To’o To’o was one of a slew of contributors to leave Knoxville via the transfer portal or NFL Draft.

This fall, the Vols must replace their top tackler (To’o To’o), top 2 sack leaders (Kivon Bennett and Deandre Johnson) and best cornerback (Bryce Thompson). Also gone are depth pieces like defensive linemen Emmit Gooden and John Mincey, as well as promising young defensive back Key Lawrence.

They’re also going through a scheme change, switching from a complicated 3-4 defense to a hybrid 4-3, 4-2-5 look.

Needless to say, with so much change and limited depth, it’s going to be a struggle for Tennessee to hold opponents at bay at times this fall.

Pressuring the QB: Worse

The Vols finished last year with 20 sacks, good for 8th-most in the SEC, but Johnson and Bennett had 4.5 each, accounting for nearly 50% of the team’s production.

Although Pruitt & Co., emphasized havoc, they didn’t have a bunch of guys who could win 1-on-1 battles outside. I’m not sure that’s changed despite a coaching switch, either.

Sophomore end/“Leo” rusher Tyler Baron (1 sack in 2020) looks like a prime candidate to take a leap in Year 2, and JUCO signee Byron Young was a spring standout, but the rest of the group is either unknown (Bryson Eason, Morven Joseph) or unproductive (defensive ends LaTrell Bumphus and Matthew Butler combined for just 3.0 sacks in 2020).

Veteran line coach Rodney Garner has a history of coaxing production out of underachieving units, and he has his work cut out for him again, as the Vols’ interior linemen offered next to nothing in terms of pocket pressure or sacks in 2020.

Former 5-star Aubrey Solomon has just 2 career sacks, same for incoming USC transfer Caleb Tremblay. Meanwhile, senior Darel Middleton and sophomore nose Elijah Simmons weren’t credited with a single QB hurry last fall.

Run defense: Worse

On the one hand, Tennessee has plenty of returning depth along its defensive line, including 5 “super seniors” who elected to take advantage of the NCAA’s extra year of eligibility, and yet, the Vols are unlikely to repeat last season’s Top 5 SEC rush defense (3.68 yards per play allowed) with a linebacker unit that’s been completely gutted.

To’o To’o, now at Alabama, had 10.0 tackles for loss — as many as UT’s entire defensive line had combined in 2020.

The former blue-chip linebacker was particularly effective filling gaps in the run game, leading the SEC in stuffs (18) during the COVID season. Quavaris Crouch, who transferred to Michigan State this offseason, was also a solid run-stopper and was No. 3 on the team in tackles with 57.

Inside depth was already a concern with To’o To’o and Crouch, so now? It’s a major red flag.

Texas transfer linebacker Juwan Mitchell, who led the Longhorns with 63 stops in 2020, should help some, but there are still questions abound at the spot.

Can Jeremy Banks return from suspension and become a consistent fixture inside? Is Roman Harrison — a raw, but toolsy playmaker — an edge guy or middle linebacker? Where do Morven Jospeh or freshman Aaron Willis, who was suspended all spring, fit in?

It’s just too many questions for a group that doesn’t endear much confidence anyways.

Pass defense: Slightly better

Yes, Tennessee’s overall defensive unit is likely to struggle, but its pass defense might actually improve compared to last year.

Maybe?

In 2020, the Vols ranked a porous 11th in the SEC in QB rating allowed, average yards per attempt allowed (8.5 yards) and yards per game (265.8), so although Thompson (team-high 2 interceptions) is gone, I could foresee improvement from a group that returns cornerback Alontae Taylor and a trio of safeties with at least a dozen career starts (Theo Jackson, Jaylen McCollough and Trevon Flowers) — especially with just a little more pass rush help.

Tennessee is going to play a much simpler scheme under new defensive coordinator Tim Banks, so the hope is that there will be fewer mix-ups and mental mistakes from the back end. A lighter schedule with fewer prolific quarterbacks (no Mac Jones or Kyle Trask) in the league should help, too.

Assistant Willie Martinez returns to Knoxville to coach up the group, and again, the biggest concern here is a lack of depth.

Behind the aforementioned quartet, there’s just three other scholarship cornerbacks — one of whom is a freshman and a converted former high school cornerback (Christian Charles) — on the roster.

Special teams: Same

Senior Paxton Brooks is back after averaging 43.6 yards per punt in 2020, 4th-best in the SEC.

With steady hang-time, Brooks rarely allowed returns either, with Tennessee finishing No. 1 in the SEC with the fewest opponent return yardage.

The South Carolina native is also a dandy kickoff specialist, generating touchbacks on 68% of his kickoffs last season. With Brooks mostly handling the duties the past two seasons, UT has ranked inside the Top 20 nationally in touchback percentage.

Overall: Worse

Pruitt played a brand of football that actually protected Tennessee’s defense the past few seasons, so with a talent exodus and a new offensive scheme emphasizing tempo, it’s very difficult to see how the Vols will actually be better on that side of the ball in 2021.

With a lighter schedule and a conference that won’t be as dynamic on offense compared to the past several seasons, I don’t think Tennessee will get consistently cooked this fall, but overall, the unit with mostly be blah to bad.