Actually, if you take out a fumble recovery in the endzone, a 100 yard kickoff return, and a safey, Pelini's defense is giving about 17 pts per game. Qualifying statistics to make an argument goes both ways.
And, as a mathematician as certified by the University of Nebraska-Omaha, I can shave a few tenths off as well by actually adding the total number of points given up through x-number of years instead of just adding the rounded averages and then averaging that, which through 2011 means Pelini has given around 19.7 ppg (without adjusting for special teams and defensive TDs scored by the opponent) But then I realize that means I have too much free time.