It will all boil down to if Iowa has mismatches at TE. If the TE's draw double teams then yeah I would hope that the WR productivity would either stay the same or increase. In other words they way you are looking at things is simply not that cut and dry.
As is the way ISU is looking at things. Under Campbell, ISU has had 2 1000 yard wrs. and neither one of those guys is on the roster now. It is kind of like when Iowa had DJK, and McNutt. when those guys where gone, it was hard to find that production.
The guys coming back are not at Lazard and Butler level for ISU and will create more issues with the offense because no one has to shade to a certain side of the field with those guys gone. Unless someone steps up in a huge way.