ISU had 6 bowl appearances, including 5 in 6 years between 2000-2005. If not the best success, definitely the best in quite some time.
If the NCAA had the sheer number of bowls during the Johnny Majors and Earle Bruce eras, those teams would be vastly superior to the ones from this decade, especially the Bruce teams, who went 8-3 3 straight seasons.
The Big 12 era is far from being ISU's most successful run in football.