The number of yards in a season is not always what makes a great running back. The greatest running back in Iowa history, in my opinion was Willie Flemming from the 1950's.
No one has equaled his talent since his great years at Iowa. Iowa's only national championship came from the AP's vote in 1958. They picked Iowa as their winner. That vote was not recognized for years, but now is part of Iowa's history.
The best running back on that great Hawkeye team was Willy Flemming. His nickname was "Willie he wisp" because of his speed and deceptiveness. He made moves that said "he was there, and then he wasn't". Nobody has ever been as good as he was at Iowa since, and maybe anywhere since. Here is some history of his greatness:
Please add him to your list of one of Iowa's greatest.