So whether it's youth, injuries, rotten performance, what have you, they Texas Defense cannot get in the way of anyone right now - except on those occasions where they manage to tackle themselves.
Texas had a ton of talent coming into the season. A half-ton of that talent is now in the trainer's room being repaired. I've lost track of who is expected back, and who is just rehabbing for next year.
Anyhoo, Texas builds itself on a lot of moving parts. Players are cross trained at many positions, so a guy who looks like he's playing LB might drop to the DE spot or float to a shallow nickel spot - only to be replaced by a blitzing S who had the DT drop. When it works, it leaves opposing OL wondering who their assignment is, and QBs wondering where the open windows are.
Obviously, this arrangement relies on players understanding their role exactly in a given deployment and given call. During this season, because of substitution, too many players have moved to too many different positions. The result is reigning confusion. Players are out of position, or (more frequently) standing static - allowing the offense to operated on a very elementary level. Defensive linemen are getting double teamed because of no fear of pressure, and the secondary just tries to keep up.
Texas probably didn't take KU seriously enough, and the new OC changed a few things for the better. However, two incompetently executed 4th and 2 calls (the decision to go for it notwithstanding - the play calls were inexcusably bad) led to unnecessary points. All this would have been a line item in the box score had Texas then not uncharacteristically turned the ball over twice within 30 yards of its own goal line (which does seem to be characteristic - turnovers are almost always underneath the goal posts this season).
KU overperformed. They're not going 0'fer in the conference. However, Texas needs help on defense, and unless players heal to preseason form, I'm not sure how to reconstruct it mid-season.