The offense was already pretty bad by Big12 standards. They ranked 8th in the Big12 in total offense (only better than KState and Kansas) . Their rushing offense with a good RB was ranked 8th in the Big12 at 120 YPG. Iowa struggled mightily running the ball this year and averaged 142 YPG on the ground.
The real strength for ISU was the defense, but they lose a ton from this unit. They lose all 3 LB in Spears, Harvey and Lanning (who was the heart and soul of this team). They also lose 2 DL and 2 from the secondary. That is a whole lot to replace, and the fact is Campbell Soup boy has recruiting rankings in the 50's so it ain't like he is getting plug and play reload type players.
I fully expect them to make a bowl game though. They have 4 for sure W's on the schedule. SDSU, Akron, Baylor, Kansas. Tech, KState, WVU, and Texas are all beatable as well. If they don't get to a bowl game, that is an epic fail really.