You are correct Homer. There has been some leakage in recent years (basically since 2010). My theory is the greater proliferation of spread offenses make it harder and harder to defend the run and by extension to get to the QB due to the ball leaving the QB's hands so fast. In college, the rushing stats include sack yards. So a rushing defense can look better than it really is by running up sack totals. I have heard KF make semi-complaints about how the NCAA calculates rushing stats over the years. In the NFL, for example, sack yards count against a team's pass yards as the offense was attempting to pass, not run.
The advanced metrics do a good job of weeding this out. And Football Outsiders didn't really like Iowa's rush defense last year either. They had Iowa's Rushing S&P+ as 52nd in the country. Full explanation at their site.
https://www.footballoutsiders.com/stats/ncaadef
I am amazed at Phil Parker's ability to have Iowa play very good team defense. It works.