We won a super bowl with Charlie Peprah filling in at safety. Our depth will be challenged at many positions as in every season. Hopefully all of the right pieces will fall together.
Our secondary is definitely a good reason to be excited for the season.
The problem is that other NFC teams have improved since then, not that we haven't been able to make due with what we have. Seattle, Carolina, Arizona, and SF of a few years ago could shut a team down while having the talent to hang a lot of points on them, while we haven't had that threat since 2010.
I'm sure the defensive unit will be good to very good this year, but not great, and without a coach to elevate their effectiveness during crucial moments, I will always be skeptical. I'm always a fan, but not necessarily of the talent procurement or coaching.