The Longhorn defense was rough last year, particularly late, in no small part because the upperclassmen in the DL didn't or couldn't deliver (Ridgeway, Davis, Jackson) and there was only one productive upperclassmen linebacker on the squad (Jinkens). The Baby Gap at cornerback and nickel was also a problem.
Online media tend to whip Longhorn fans into a frenzy with the idea that "impact freshmen" will decide the season (recruiting drives subscriptions), but 450+ yards per game surrendered, the shaky run defense that characterized the season's home stretch and a 5-7 record is a testament to what starting lots of freshmen talent actually yields.
With that in mind, let's dive in on the importance of defensive upperclassman contributions:
DL Boyette, Ford, Hughes, Cottrell, Vasser
They will determine the performance standard of the defense. The freshman DTs will be asked to contribute early and often (they're basically the depth chart under PB and The Poonatrator - coming soon to the WB Network!) and while a Rodrique Wright debut year from one of them isn't impossible, it is improbable. So let's cool our jets on the two freshman starters at DT against Notre Dame chatter. Boyette and Ford need to step up their games inside and stay out of the trainer's room. You don't have to dominate at DT in this league to defend well, but bad or average comes with a price.
Similarly, veteran Naashon Hughes has to tick up from solid to game-altering. Bryce Cottrell has flashed at times - there's something there, right? - but now it's time to win a Gaskamp Award. JUCO Quincy Vasser has thus far underwhelmed, but he did show some signs of life in the Spring game. Sometimes I sing JU-CO HERO to the tune of Jukebox Hero by Foreigner. It's pretty satisfying. Try it.
LB Tim Cole
He led the Spring game in tackles, but some rough patches in game action spot duty aren't easily forgotten. There's pressure on Wheeler to deliver and for Edwin Freeman to be first man off the bench.
CB Evans, Davis
Sheroid Evans and Antwuan Davis certainly look the part. But injuries have plagued Sheroid's career and Davis hasn't made plays when the ball in the air. Evans locking down a starting CB gig opposite Davante Davis or becoming a kickass 3rd corner (check the greatest Longhorn secondaries of all time - every one of them had a stud 3rd corner) for our nickel and dime man-under looks would be fantastic.
S Haines, Hall, Vaccaro
Haines is starting until someone demonstrates a similar fluency with our calls and debating this point has grown tedious. What is worth discussing is whether 10 pounds of weight gain will help him deliver some tackling pop and if upgraded personnel around him will expose him more favorably. He was arguably more effective in '14 than '15 and the supporting cast played a big role in that.
Jason Hall's was definitely better in '14 than in '15 and his gig isn't secure unless he can consistently bring the pain in run support. Vaccaro is a tough-minded athlete who can provide attitude and motivation for more talented, less focused peers.
This defense fails if Boyette, Ford, Cottrell, Hughes, Haines don't show improvement. Guys like Malik, Omenihu and Davante are the upside, but we're talking about infrastructure. They'll fall from the heights without scaffolding. The big upside upperclassmen value-add is found in a healthy Sheroid Evans or, perhaps arguably, a rejuvenated Jason Hall.