It is an interesting trivia piece but it is one of those stats that could mean a lot of different things. The Big Ten is not a pass happy league at all right now so 300 yard passing games are not the norm and have not been for a while. We also are not blowing teams out on offense meaning they don't have to throw a ton to try and play catchup.
All that said it certainly points to what we all have been well aware of, we have had a really solid secondary that makes passing tough on most of the teams we play.