There's not a single person here who is perfect at their jobs, and it usually takes a dark moment to occur to spur one into truly changing. Apparently the Nebraska game was exactly that.
But to lay the (so far) success solely on CJ over JR I think is simplistic. To me, the changes appear in many respects across the board yet subtle in each facet.
At best, I'd label them as across the board tweaks. It's not like they suddenly went to the read option and 46 defense, and he changed as far as his public demeanor becoming the second coming of Bo Pelini.
Kirk didn't need a wholesale makeover because Iowa football still needs to espouse the things that usually translate into success here at Iowa. We ALL know what those are. The formula is still exactly the same as it was last year. Just needed some sanding and polishing and tuning up some things that were unnoticeable to Kirk before the 2014 Nebby game. By his own admission. He knew then he had to change...it's just the bowl game wasn't the time to do it, too short a timeframe to start that many changes.
And quite frankly...I don't think we see what we see now without the Tennessee game occurring the way it did. It's like "The Moment" came when he yanked Jake in the first half. True Change started right there.