Bit late to the conversation on defense but I wanted to talk about our upside and ceiling on that side of the ball
I charted all of Tech's traditional run plays (i.e. handoffs) from the weekend (there's probably a couple errors but w/e). Their average yards before contact (YBC) was .55 with half of my charted plays involving contact at or behind the LOS. That's really really good. I can't find a college football YBC stat, but the lowest YBC of any NFL RB last season was 1.2. So .55 is likely an elite number. I think it speaks to the ability of our front 6 to get penetration while maintaining gap integrity. Seriously, all of our DL take turns getting in to the backfield and Overshown/Mitchell, for all their flaws, have been good about meeting RBs in the right gaps. We lost containment on the edge a couple times, but there is enough athleticism and physicality in the secondary to minimize the damage that would cause. All in all, Tech ball carriers only got to the secondary untouched twice on Saturday (once on a jet sweep, once when because Overshown was being held very clearly but there was no call).
Of course, YBC sounds good but doesn't matter if you can't get the guy to the ground. That's why their team had 4.8 YPC, an extra 4.3 yards after contact (YAC). 2 extra yards would be fine, maybe even 3, but 4+ is god awful. Derrick Henry led the NFL at 3.2 YAC last year. Everybody knows that tackling was absolutely horrendous so I'll just add that there's no real reason for any of us to expect significant improvement. We'll be better than we were against Tech, but I'm just going to expect double digit missed tackles per game. (That's one per drive! Pretty dismal)
So when I look at this Texas defense, the hope has to be that they shore up tackling just enough to be an elite run defense (Overshown could accomplish this by himself) and make teams one dimensional. Of course, Big 12 teams will happily throw all over you. And that's gonna happen. We have athletes at LB and DB but they're not as well developed as the skill players they'll be lining up against. So I expect teams to light us up in the air, but I also think we can steal a couple possessions per game with negative plays and turnovers. I think if we can end up with a ppg average (conference only) around 27-30 (that's the same level as OSU, WVU, and TCU last year and slightly better than our own) that our offense should be good enough to win 9+. Hell, OU won the conference giving up 37.6 in 2018, although our offense won't be that consistent.
So to finish up: is our defense going to be good? No. Can it be good enough to win the big 12? Yes. Marginal improvements in tackling will make us an elite run D. Shore up LB drops in pass coverage and the pass rush and we're on track for a CCG berth.