The pass defense played better yesterday than I expected against a good passing offense like Detroit. It helped that we got a lead and could emphasize a conservative deep coverage defense. Even Cook seemed to be playing a bit of a deep zone at times. A number of dropped passes by Detroit helped, but I think the secondary should be given a fair amount of credit for their performance yesterday. As well as the DL of course ;)
I will agree with your overall point though that the Cover/Tampa 2 defense is still a valid approach as long as you have the right talent and execution.