They replace their top three line men. The last time they did that was 07'. Look at their record then. Those RBs will have a hard time finding holes
In 07 Iowa's starting offensive line consisted of a true freshmen (although it was Bulaga, he was very young), two true sophomores, a JR and a SR. In terms of playing experience, those 5 guys only brought about 12 seasons of experience on that 07 line.
This years starting line up:
LT Reiff (3rd year SO)
LG Gettis (4th year JR)
C Koeppel (SR)
RG Vandervelde (5th year SR)
RT Zusevics (4th year JR)
The 2010 line will bring 20 years of experience to this offensive line. A comparison between the 07 line and 2010 line would not even be remotely close to accurate. I'm not saying the 2010 line will be anywhere near as good as the 02 line was...but I think this offensive line will surprise a lot of people.
The key component to Iowa's OL working well is to have it be composed of guys that have a lot of experience in the Iowa system. 3/4ths of this line will have been in the Iowa system for at least 4 years, and the one guy who hasn't been in the system for 4 year is Riley Reiff, who is Iowa's most talented OL.
If you expect this Iowa OL to be bad, or anywhere nearly as under achieving as the 07 line, you will be sorely disappointed. I don't know how deep this OL is, but as long as injuries don't become a huge problem, the starters will be more than adequate.