The Super Bowl champions lost their final pre-season game to the St Louis Rams on Thursday.
The head coach told reporters: "We've got concerns everywhere. Every single spot we're concerned about. We want to make [this team] as good as we possibly can in every way we can.
"It's a long season, so the improvements that will be made between week one and week 16 will be dramatic, we hope. This is the beginning, really, of the season. At this part of the season, we've worked as hard as we can work, and that's what I like about our team.
"We work really, really hard. We've got a tremendous attitude. We're probably as far along now as we possibly could be. How far that is we'll find out Thursday night. But, it's an opener, and openers are what they are, they're unpredictable. So, we'll just have to see."
The Ravens play the Denver Broncos in the opening game of the NFL season.