Before that, Bo Scaife was hurt every year - until he wasn't. It's like Spinal Tap's drummers.
That, though, is the reality of the college game. If your important players didn't sign, didn't make grades, or got hurt, you can't go to the waiver wire to keep running your favored schema. You have to be ready to go into team meetings on Sunday and say, "OK, here's how we're thinking on offense this week!".
Losing Brewer and Colin Johnson was a significant hit to talent, and no doubt. However, the plays Texas ran showed me that they just didn't have the intellectual capacity to scheme with the players they had. So many versatile pieces could have easily been repurposed without a huge learning curve. The OCs just never did their homework.