I think a more objective look would be to grade each team at it's specific positions:
Team:------SF------Hou-----Ten-----Cle-----N.O.-----Oak-----Det-----Buf
Position:
QB:-----------D--------C-------B--------D-------A--------D-------B--------D
RB:-----------C--------B-------B--------B-------A---------B-------B--------B
WR:----------C---------A-------C--------C------B---------A-------B--------C
OL:-----------D---------D-------C--------C------D---------C------C--------C
DL:-----------D---------C-------C--------B------B---------D------B--------C
LB:-----------B---------C--------B--------B------D--------C------C--------A
CB:----------D---------C--------B--------C------B--------D-------C-------A
S:------------D---------D--------D-------C------C---------D------C--------C
Aggregate
scores:-----(D+)----( C )------(C+)----(C+)---(B -)-----(C-)---(C+)----(C+)
I'm certain I've left myself open to some criticism, but this was the best I could without spending all day researching. Speaking of research, I toggled depth charts on NFL.com to formulate my opinion. This is just my opinion and any input others would like to inject would be helpful.
Somehow, the Saints came out way ahead of what I would thought. I guess their skill position guys really vaulted their score. In review, I think the Bills landed where I would have figured among these teams. Better than SF, Oak, and Hou. On a par with Det, Ten, and Cle. Surely not the worst talent in the league, but not too far away.