Well, last season, ISU went 7-6, with a win in the Insight bowl over Minnesota. They were 6-6 regular season, and 3-5 Big 12. However, you really have to consider a couple things.
1) Their non-conference schedule last year consisted of Kent State, Army, North Dakota State and Iowa. This year they face Northern Illinois, Northern Iowa, Utah and Iowa. Northern Iowa has beaten ISU, and nearly beat Iowa last year. Utah's pretty good... Point is, while last year ISU's non-con record was 3 solid wins and 1 solid loss, they don't have that sort of 'guarantee' of wins this season.
EDIT: Last year's opponents not named Iowa went 5-7, 5-7 and 3-8 last season. This year's opponents went 7-6 with bowl loss (NIU), 7-4 (UNI) and 10-3 with bowl win (Utah) last season.
2) They replace Baylor, Ok State and Tx A&M with Texas, Oklahoma and Tx Tech.
A&M may be better than Tech this year, but Tech is still pretty good.
But point is, ISU only has so many "probable wins" this year, in NIU, UNI, Kansas, perhaps Colorado or KSU. That's only 5 wins. You already need an upset of sorts just to make it to 6 wins. Lose to NIU in week 1 and you're going to have to upset two teams to make it to 6 wins. Not impossible, but definitely not the pressure you want to place on your guys just to reach 6-6.