I feel your pain. I’ve gotten incredibly frustrated at the Ravens in the past for exactly the same thing. Here’s a post i made during the playoffs in January, 2010:
I think it’s become the football equivalent of walking a big hitter in baseball. It’s often a bad idea, but it’s done because it seems like the “safe” move and fewer people are likely to criticize you for it.
If you walk Albert Pujols or Prince Fielder and they end up having a big inning, no-one blames you for walking the star hitter, but if you don’t walk them and they hit a game-tying home run, everyone asks why the hell you didn’t put them on.
Similarly, if you play the Prevent defense, and end up giving up a touchdown, you probably won’t cop as much shit as if you continue with the regular defense (including the blitz) and end up giving up a 50-yard TD pass or a long run. If you play your usual defense, and give up a long touchdown, everyone then spends all of Monday second-guessing you and asking why you didn’t drop guys back into a Prevent defense. It’s the “Don’t blame me” strategy.