Almost without fail, whenever Iowa loses, Kirk Ferentz points to a "failure to execute" as the problem. A huge number of Iowa fans would say the real problem is that the offense is "vanilla" and "predictable."
Who is right?
In my opinion, Ferentz is right, but there is more to it than that.
Nevertheless, for the time being, just consider Iowa's offense. It is a pro-style offense that uses primarily ace, pro, and I-formations. Iowa still regularly uses a fullback, despite the fact that the fullback is being replaced by the H-back, both in college and the pros.
The Hawks also use a lot of tight ends, to the point that Iowa's second tight end is virtually a starter.
If you looked at the above links, you will have noticed that Iowa is decidedly not a spread team. More often than not, they keep a lot of players in a small area. As this is the antithesis of the spread, it invites defenses to blitz and drop safeties into the box.
Moreover, as silly as it sounds, it's a lot like football video games, in that a spread offense makes it easier for a player to see what's going on, because everything isn't bunched into a smaller space. When you play EA Sports NCAA Football, you have more control with the spread offenses.
Actually playing football is considerably more challenging than the video games, but the concept is still the same.
Due to this, and due to Iowa's pro-style formations, the Hawks need to execute more consistently and efficiently than a spread team like Michigan or Purdue.
Needless to say, it is asking a lot for a bunch of 18-23 year olds to do this, particularly if NCAA rules only allow them to spend so much time per week practicing. Consequently, it is no surprise that the only year that Ferentz had a top 20 offense was 2002. That year, he also happened to have four soon-to-be NFL offensive linemen, one soon-to-be NFL All-Pro tight end, and a Davey O'Brien Award winning quarterback.
In essence, this is the primary reason that the spread offenses are in such vogue in college football; because every single player doesn't have to execute as well on every single play in order for the offense to be successful.
Mind you, I am not advocating for Iowa to become a spread offense. Far from it, as there is very little that I find more boring than watching Rich Rodriguez's Michigan offense (yes, I realize I am in the minority).
Still, Iowa could run out of more three-wide sets, or use a lot fewer fullback looks. Basically, the less defenders in the box, the less perfect the execution has to be, and the more Iowa can withstand a mental flub on the part of one of its players.