Who exactly are the "top tier" defenses? Denver and...?
Edit: Seattle, who else
NFC only,
1. PHI
2. ARI
3. MIN
4. SEA
5. NYG/GB/Rams
Football Outsiders has the Eagles defense ranked 1st. I don't know if we're just dismissing all stats sites these days though.
PFF is highly subjective, that is why it was dismissed. Better to treat their grades like an opinion.