Minus the OLine getting worse, both by subtraction and the fact that Martin has gotten older in a hurry, and the running game getting worse, both due to worse personnel and an inferior OLine. On defense the team is missing its best players and because the offense is weaker they can no longer get a lead and force the other team to pass it. Forcing the other team to abandon the run was basically the only reason the defense last year looked good and it is why power run teams dominated the Cowboys. Basically you can trace the defensive problems back to Mazi Smith being a bust.