Not sure I agree. I've seen people repeat that time after time but not sure it's fact. That 2002 team may have continued to improve anyway... Beating ISU wouldn't force us to lose against PSU or Purdue nor did what was a 5th straight loss to ISU "stoke the fire" IMO..
Fumbles seemed to be a problem early that year, and it sure was what got us beaten against ISU. Fred Russell fumbled at the goal line @PSU, where a TD would have totally put that game away, but let them hang around and make a comeback. I believe KF would have gotten the fumbling problem corrected regardless of whether Iowa lost to ISU or not. That team had the talent to be great, and they were. They just fumbled away the ISU game, literally.
Purdue - Joe Tiller's teams always gave us fits. Just was a bad match up. PSU & PU were the only real close calls I seem to remember that year. Purdue also nearly knocked off OSU last day of the season, except for a lucky late TD pass to save OSU's bacon, if you recall.