re: Is anybody worried about the defense?

According to insiders, Saban was pretty happy with the defense this spring, as they were much further along than he thought they'd be. Considering the injuries last year to our key pass rushers, we might actually have a better pass rush this year, and Deionte Thompson is an absolute beast

We'll likely have the best defense in the country again

In other words, no.
The ONLY thing that would keep us from a national championship this season is if Tua were to get hurt. That's the only thing I'm worried about