FWIW, I fully expect the defense to get better as the season wears on (if they're not totally exhausted by the bye week). Washington, Williams, and Toler are rookies (essentially); Rhodes and Lenon are being integrated into a new system. As these players become more comfortable with their roles, their play ought to improve.
The downside is that Joey Porter looks finished, and Clark Haggans is being asked to provide a pass rush he cannot produce. I expect their play to wear down as the season progresses, which is much, much worse.