They're front runners. When you're forced to pass, they can rush the passer as well as any front line.
As such, they're susceptible to traps and double teams, misdirection runs, and cutbacks. That's where the LB's are supposed to come in. But LB's get caught too close to the line of scrimmage, and often can't cover the holes because they can't get there with the big bodies flailing around in front of them.
9'ers have always had good misdirection runs, traps and cutback blocks. They seldom can push anyone backwards, as seen in the Detroit game. Most of the gains happenned because half the Detroit DLine had penetrated past the point of attack, and needed to recover and run down the field to chase down the RB's.
That's always been the cure for the pass rushing teams...ram it down their throats. But you gotta account for the LB's 3 yards behind scrimmage looking to cover gaps in the DLine.