Well I'd say defense is Detroit's most glaring problem (last in NFL in both YPG and PPG given up). And Schwartz certainly put together a nice one in Tennessee. I might have prefered Rex Ryan from Baltimore if they wanted to go the defensive coordinator route, but they might not have been able to get him. Rumors are he is going to the Jets.
Schwartz sounds like a solid hire though. I just hope, for his sake, that Lion fans aren't expecting a Miami Dolphin-type season next year. The rebuilding in Detroit is going to take a little longer I think.