Players leaving or not showing up are NORMAL in all college football programs across country.
However, in the first two years of the Zamberlin era 23 of the 46 commitments are not longer with the program and only 11 of the 28 Freshman kids recruited are still in the program. These numbers may be off a smidge, but overall, they are pretty damn close.
Some of this should be anticipated with a new coaching staff. You cannot average keeping 5-6 kids in your freshman class per year and expect to build leadership, stability, chemistry and depth in the program.
Next, you need to start worrying about APR issues and a possible reduction in scholarships. At this pace, I would say that ISU is in danger of getting penalized two to three years down the road.
I will bet that these number will improve quite a bit with this current class. The 2009 class is already better off than both of the first two classes combined. I expect things might improve quite a bit.