First, opponents started with poor average starting field position (29th best nationally). Second, they were fairly good at preventing explosive plays (7th fewest nationally in explosive plays per rush). As a result, while the yards per play were high, the EPA per play was lower (nationally average in nominal terms, top 40 when adjusted for strength of schedule). Finally, while Iowa State didn't turn teams over at an exceptionally high rate they made the most of the turnovers they did force, which resulted in a high EPA per turnover.
On offense, Iowa State again outperformed its fundamentals. They were not good on 3rd down, gained 25 or more yards on only 3% of plays, and were below average in EPA per pass and per carry, and yet the offense was slightly above average in adjusted effective points per possession (EP3+). They didn't score a lot of points on those possessions, but they tended to turn bad field position into good field position for the defense. It's a silver lining.