The Maryland game had to happen.
Texas has talented athletes at every position. What they lacked was trust. Someone would miss a tackle or alignment, his buddies would get to thinking rather than playing. They'd try to anticipate mistakes rather than play their position. It led to everyone getting to the ball a second too late.
During last summer, the defense learned to trust the coaches and each other. They spent the whole summer learning to rely and scheme and their buddies. They were ready!
Then, during the 2nd quarter of the Maryland game, they faced adversity. Someone made a mistake. The team panicked. They forgot what they'd practiced, and went right back to playing like they had the year before. As a result, mistakes created mistakes. The snowball rolled just enough that Texas stood on its own field looking like the kid who threw up at his own birthday party.
I believe Todd Orlando used that tape. I believe he asked his unit to try things his way. Don't think. When the scheme is called, know your role. When the ball is snapped, execute it violently. Trust that your buddies will do the same. Mistakes will happen. Tackles will be missed. Get right back up, and go again. In the end, the opponent won't be able to match your intensity, and they'll be forced to react to the defense - rather than dictate terms.
Before you're old and wise, you have to be young and stupid. It's why we like older players. They've got talent, yes, but they've already made the mistakes and (hopefully) learned. The defense had to come through Maryland in order to prove that trusting your coaches and teammates was the way to go. It's now up to the players, as they age out and new ones come in, to teach that lesson.