It was only Hayden's third season. And the fact is Iowa's offense was vastly improved and wide open from the very first snap of Hayden's very first season in 1979. Iowa threw the ball effectively, and Hayden introduced various trick plays, including the statue of liberty and the flea-flicker.
But yes: Hayden understood that defense wins championships, and he always coached that way. But he also understood that it's important to complement a great defense with the best offense possible.
BTW: I was there for that 1981 upset of Nebraska, and it was awesome, especially so since I was also in Lincoln the year before to see Iowa fall 57-0. To come back one year later and beat another top ten Nebraska team 10-7 was one of the greatest wins in Iowa history, IMHO.
And when Iowa fans started chanted "Rose Bowl! Rose Bowl! Rose Bowl!" in the waning moments, it was with a smile of wistful hope. Few, if any, realized they were making a prophecy, for that 1981 Iowa team actually did go on to share the Big Ten title and make the Hawkeyes' first Rose Bowl appearance since 1959. . . in only Hayden's THIRD year on campus. So yes, I believe in miracles.