I think these are all good pieces of the puzzle. I wouldn't ignore the 8th ranking in total yards, that's a piece, too. Good for you for doing the homework on it. I'll give you credit that you aren't just whining about how bad the defense is without some data to support your assertions - like some posters are wont to do.
I think average is about right going by the unscientific and always skeptical eye test from a year ago. I'd be curious what our ranking was the last half of 2017. Not that I expect you to do that research, and I'm probably not going to spend the time breaking that down - unless I get bored.