It's simply a strategy that everyone uses. In fact, the Tampa 2 defense is pretty much predicated on it. Don't let the defense get past you so that they can't score quickly and need to burn a lot of clock getting downfield. Dungy and his Tampa 2 plays two deep, allowing short dumps and expects the speed of his defense to stop the dump before it turns into a long play.

But there is the the thing, there's no reason why we couldn't play two deep, and still keep the pressure on, rushing four, do some stunts on the line, and play more of a normal defense as opposed to letting the prevent get picked apart. And no, Haslett should not be fired, just reminded to keep up the heat.