Using the prevent is just playing the odds. Keep everyone in front of you and let the clock be your friend. The Steelers went to a lot of heavy blitzes on Baltimore's final possession last night, they got burnt on a couple of passes to the deep corner, 1 for the TD, one that should have been caught several plays earlier. The knife cuts both ways, if you bring pressure, you better get the QB or you're just leaving your secondary exposed. Of course it works infinently better when you can get pressure from your front 4, which the rotation and combination of Johnson and Dunlap has worked great for the Bengals so far.