Setting aside the horrific play of the special teams, the Lions could be 4-0 if they had done a better job of holding onto footballs and holding onto opponents at key moments. That is what they have to fix.
The defense needs to tackle the pedestrian Michael Crabtree on checkdowns. DB's can't let the average Titan receiver pluck balls off their helmets and run 60 yards for a TD; the receivers have to catch the TD’s and the first downs against the 49ers, Titans and Vikings; Raiola has to NOT snap the football on those fakes. Don't fumble. Turn and look for the ball and avoid PI's. Know your blocking assignments. Basic stuff.