I have posted this a few times in other threads, I will repeat one last time and then quit beating the drum. Weisman has 937 yards rushing this year. He had 815 last year. Of those 1752 yards, probably 90+% have come on outside zone. Like most zone running teams (i.e. just about every NFL team and most college team's that run a pro-offense), Iowa's primary running play is outside zone. It is not meant to be a sweep, it is meant to break off-tackle with an alley heading towards the sideline. When it works (think Weisman's 11 yd near-TD against Neb, or his 22 yd run on the icing drive against Mich), that is exactly what happens. When the D can maintain their gaps, it gets strung out and goes for little or no gain. Many fans think the play that gets strung to the sideline is an outside zone, and the 10 yard gain off-tackle is something different. They are the same play. You can tell by watching the initial line steps and the manner in which they work off their double-teams.
Inside zone is intended to take advantage of a defense over-pursuing to outside zone. Initial line steps are similar but usually not as wide, and the O-line will try to drive more up-field as opposed to sealing their man to the inside. The crease usually opens to the backside, whereas the outside zone crease is an alley towards the sideline on the play-side.
Iowa will occasionally run some iso or power, but their outside zone is their bread-and-better and accounts for most of their yards. Not to go all, "Know the game!" on you, but fans that criticize the Weisman outside zone for never working are just plain wrong and are demonstrating a lack of understanding of the game.