Exorbitant
An image back in time
"Softening up the D" is a myth. Just look at the stats for this year...the average YPC for the top ten rushing teams goes up 0.056 yds/carry from the first half to the second half, or all of about 2 inches per carry.
Try asking someone in the know about this. Maybe someone like Osborne? The statistics you posted here are misleading. Do you remember what Wisconsin did to Nebraska this year? In the second half the Nebraska defense got really tired and then got pummeled on the ground, by a better coached football team.
Tons of times Nebraska under Osborne wore out defenses, and by the 4th quarter, defenses were shredded.