OK sorry to be a nit but, trenches are always important. Whether or not it's more or less important than usual, I don't think has anything to do with how good a team's lines are. I hope that makes some sense.
As for keys, I've gone into pretty much every Bills game for 10 years thinking that our offense was the key. I think I've been right for the most part. 7-9 and 6-10 in 1997/2003 with a good defense and 8-8 with a terrible D in 2002 is pretty good evidence of this.
For some reason, I get the feeling that our defense is going to decide our fate this season. Maybe it's because for some inexplicable reason, I like our offense a little bit this year providing a lack of JP brainfarts. I think fans of about 20 teams think their OL stinks and I don't think ours is much worse than average and I think our skill guys can play some. I dunno, I just don't see us losing many 13-10 games this year.
I know Brad Johnson has won a lot peoples respect lately (me included) but their wideouts scare nobody. Our run defense makes me cringe; if we keep Chester Taylor under 80 yards we'll be in 1st place Monday. So yeah, I guess I agree that trenches are big.