Great, the defense is limiting points with great red zone efficiency. But, that doesn't help the offense score points. Good field position helps the offense score points.
So, when you have an offense that is using redshirt candidate QBs who haven't been in the system or you combine returning QBs with inexperienced receivers and your RBs are weak and not nearly as strong as what you had the previous year, then the offense is going to struggle. They're going to need help.
Why did Critchlow look so good against UNLV? Because we won the average starting field position by 25 yards. Our avg starting point was our own 40 yard line.