It is explained by pressuring the QB with the D line and dropping LB's back in coverage to assist a weak secondary, vs pressure from the front seven. After the Chargers game, the Ravens figured out that trying to provide additional coverage downfield did not work if the QB had time to find open receivers and throw. Once they started to blitz more, they stopped giving up big passing yardage like they had been, and got more sacks.
Granted, maybe not against elite QBs, but the plan is essentially the same. And I am sure that is the plan Pees has in mind for tonight. The Ravens cannot allow Ben to drop back, stop, stare, whistle Dixie and find an open receiver 6-7 seconds after the snap. Yeah, he's good enough and mobile enough to elude a pass rush and still find an open receiver, but such pressure can force an INT or get a sack and maybe a fumble. Leaving him back there with limited to no pressure will be a disaster.