Is the Ravens defense really that good?

You could say the same thing about our offense.
Look at the defenses we have played.

Cleveland (22nd)
Green Bay (32nd)
Atlanta (20th)
Carolina (17th)
Tampa Bay (27th)
Philadelphia (16th).

We have not played one team with a defense ranked in the top half of the league.

As far as Baltimore goes, the are very good against the run and have used 6 and 7 people to stop the opponents rushing game leaving a lot of players against the pass. They aren't great at rushing the passer and Carolina proved that you throw against them but our passing game is very different to Carolina. We will see in a few hours.