It's very simple.
Yet it's something that folks can't seem to grasp for whatever reason. Just like if I told someone that the probability of flipping a coin for 1,000 straight heads is the exact same as any other random combination. You can show people math and facts, but it doesn't register because they get blinded by either stupidity or the hubris of thinking their team (a la nebraska) is much more relevant than it actually is.
The simple fact is this...coaching changes end up with worse results way more often than not, and at the very best they replicate the same poor results. Only in a VERY few instances does a coaching staff come in and improve things, and even rarer yet is it that a staff comes in and improves on a staff with a WP north of .700. To do that would require luck akin to winning the lottery.
That's all fine and dandy if you're a team with a garbage record, or a lot of scandal, or you're already playing musical coaches. But if you aren't...if you're an Iowa team that has had 42 years of stability, been relatively scandal-free, has a rabid regional fanbase, and success that many teams would kill for (yes, more programs than not would love to be in our shoes whether you're happy with it or not), it's monumentally stupid.
Essentially what you're doing by saying you want a different staff is equivalent to,"I've spent $1,000 on scratch tickets but only broken even. I'm going to buy $1,000 more because surely I'll win this time." Because of hubris, you've completely ignored the fact that you've been unbelievably lucky to break even. And even dumber yet you think the odds of better success are in your favor (which they are absolutely not).
Truly elite coaching staffs are not assembled with skill. Elite coaching staffs are a product of luck that makes administration look like they knew what they were doing, as well as recruiting power. Iowa does not have recruiting power, so that leaves luck. And terrible odds.