The problem with a bumpy braking zone is that it destabilizes the car. If the bumps simply reduced braking, not a problem as you observe, you can overshoot the corner entry and go into the runoff.
The crash video from the 1/2 mile event shows the car running off the right side of the track and into the grass, then tumbling -- at that point the amount of additional runoff available is unfortunately no longer relevant
This.....hard on the brakes + bumpy road = hold the **** on