It's possible, but teams that generally make a bowl game do have a better offense and score more points. In the four games we lost last year, the defense was poor and the offense was worse. The defense didn't bother to show up at Cincinnati or against BYUIf 20.2 is the average number of points we gave up per game, why would it necessarily have been higher if we had played more games?
If we had played in a bowl game with our normal roster, we would have likely been matched up against a team that would not have been nearly as familiar with our defense as our regular season opponents. It's possible we would have held them at or below our season average. Regardless, the result of one game would not change the 20.2 average very much.