2011 (last winning season w Linehan) was a long time ago. Different team and players. And even then Linehan wasn't beating winning teams.
This years defense has obviously suffered an colossal drop off without Suh. Last year, through the first three games the D surrendered 45 points (including 3 at Minnesota).
This year through three games, they've surrendered 83. Damn near double.
Edit: 45 points (and then only 3 at Minnesota later in the year).