Analysis: Raiders' prevent defense failed

The joke goes like this: The only thing a "prevent" defense does is prevent you from winning. Proof positive? The Raiders' heartbreaking 24-20 season-opening loss to San Diego on national television, a game in which Oakland outplayed the Chargers for three quarters before said "prevent" defense was instituted. You know what happened next. Chargers quarterback Philip Rivers carved up the Raiders, taking with aplomb what was given him underneath. Consider: In their last two drives, the Chargers gained 166 yards after getting just 152 in the first three quarters. Yes, there are times when such "soft" coverage works by allowing minimal gains in the middle of the field as the clock runs. But when the ballcarriers are not only allowed to get through the line of scrimmage, which the Raiders had dominated to that point, but break away for impressive gains and then also get out of bounds to stop the clock, that's when prevent defenses are...