I like your approach of dwelling less on what they have been, and focusing more on what they can become.
When considering what the Ferentz-era Hawkeyes have been, all reasonable fans (and those within this conversation have been reasonable) vary somewhere between, "He's been a slightly above average coach, but I think we could do better" to "He's been a well-above average coach, and it is far from a sure bet that his replacement will be as good."
But no matter how you consider what he has been, what really matters is, "What gives us the best chance to close the gap on and surpass Wisconsin?"
Considering what Iowa has been (2nd tier in the B1G West below Wisc), and the recent changes in the program (e.g. recruiting changes, staff changes), do you think the gap is going to close? If not, it should be time for a new coach.
Personally, I see enough signs to be hopeful over the coming seasons. They have been solid if not spectacular, as Dean has pointed out, with lower-level recruiting and a below-historical-averages offense over the last 6 years. Their recruiting is on the uptick ('18 class is best in 7 seasons; last 3 years are 4th best 3-year stretch of KF era; 10 '16 and '17 recruits on last year's 2-deeps on each side of the ball). They also have a young offensive staff who might have unrealized potential as they are all settling into their roles (the optimistic view), or who maybe are not that good (pessimistic view). I am not sure their ceiling, but they have to be improved this year with more experience.
I try and stay in the moment is all. A wise man once said that to live in the past causes depression and to live in the future causes anxiety.
While I do agree that stars or class rankings are important, they are not the end all to be all.
I do however think that the current staff knows what to look at for intangibles. In other words, I'd take this staffs top 25 class over any ranked above it. Especially given the coaching abilities and now the facilities.
So yes, I think we are pretty close to taking over the West. Which certainly wouldn't hurt recruiting.
Which brings us to this class, including walk ons.
It's a pretty special thing to be part of an era of change for the better.