I don't see an aggressive approach in any other part of the offensive game plan - until they have fallen behind. This is same old Zimmer: try to run the ball and minimize passing. If they have a schedule full of weak teams, it works for those and he pads his record. Against better teams, they get stuffed and fall behind and start throwing desperately, when opponents know they have given up on the run, and it generates some yardage and points but also sacks and INTs.
Another thing about Zimmer's teams: they often come out and score on the first series of a game - but then fall behind and out of the game. Does he think, "We're up 7-0 or 3-0, now I can protect the lead and play conservatively"? 7 points in the first quarter is not a lead to protect, it's a lead to expand!! I honestly don't know if they score early and collapse so often because he gets conservative, or because they have only one well-planned series to start each game and nothing beyond that.