It was definitely frustrating to watch the offense struggle in that game, and i agree that Leinart was mediocre - but i have to disagree with your shifting ANY blame for the defensive collapse to the offense. Prior to the Titans' final drive, which took the last 2:37 off the clock, the time of possession was almost dead even, with the Cardinals having a slight edge, at 28:53 - 28:30, and each team had run exactly 52 offensive plays on 8 drives (Cardinals) or 9 drives (Titans).
The ineptness of the Cardinals' offense in that game did not result in the defense being "on the field all day" nor give the defense ANY excuse for their 99-yard letdown. The D had played adequately, but not particularly well, for the whole game, bending but not breaking while giving up 433 yards BEFORE the final drive, 532 total.
Leinart had played a safe, conservative game, 21-31-220-0-0 - which is probably exactly what Whisenhunt wanted from his backup QB against an opponent with a good defense and Vince Young at QB. Keep it close and leave it in the hands of the D. Leinart kept it close, but the D let it slip away.
...dave
[Whoops... just got to the last page of the thread and see that Joe beat me to posting the info about time of possession.]