Wrong.
The offense in itself was fine. In reality there were two different problems:
When things were going good: Any time McCarney got a lead, he was always afraid of his offense making the big mistake - the critical turnover that would swing the game in an instant, one from which his team would never be able to recover from. To his credit he had some really good defenses late in his tenure and his expectation was for the defense to go out and win the game. The problem is, as good as the defense was, the lead was never that large (usually no more than two possessions), so opponents would chip away at the lead, and eventually ISU would find itself tied or down. Unfortunately, by that time, the offense was completely out of rhythm and never could kick it back into gear to win the game. This was best exhibited during the 2004 and 2005 seasons.
When things were going bad: The offense was so predictable that everyone - the opponents, the fans in the stadium, everyone watching at home - knew what play the offense was going to run before the OC called the play - usually it was run up the middle/run up the middle/3rd and long pass play/punt. Even if the defense was good, they got no support whatsoever and were left hanging out to dry. This was best exhibited during the second half of 2002, 2003, and 2006.
At the time we switched to the spread under Chizik, few teams in the conference were running it (mainly Texas Tech). That was when virtually everyone in the conference switched to it. ISU is in a situation where it has to be distinct from what everyone else in the conference does. And you can be just as creative running a Power-I as you can be running a spread. What you need is an OC that knows how to run an offense effectively and isn't hamstrung by a defensive coach (as was the case with McCarney, Chizik, and now Rhoads).