If there's anything we've learned from past experiences with coaches in other sports, 100% buy-in from the players who stay is absolutely necessary. How much more with coaching staff? Coach Sam excelled in recruiting certain types of players for what has become the new standard for women's basketball teams. Maybe what Caldwell wanted in her players were features, capabilities, attitudes that Coach Sam had never been called on to look for. Maybe she didn't have the radar for finding those players. And, if so, it wouldn't be hard to understand that she might not have 100% buy-in to offer CKC. And thus they part, as happens dozens of times in every sport every season.
Try to remember what we were thinking and posting about Barnes when he arrived (coasting into retirement was the common fan accusation), and him recruiting some 3-star chess champion who was headed to an Ivy League team: "he's too short to play inside in the SEC, and if he wasn't why weren't other schools recruiting him?" But Barnes knew he wanted Grant Williams--for reasons none of us could see from our perspective or the stats--and he was proved correct.
Didn't Heupel at the last minute pick up some QB from VaTech who had already gotten beat out of the starting position there by an underclassman? The best we fans could say about that move was "not much eligibility left, but maybe a decent stop-gap backup if he can learn the system quick enough." I'm pretty sure every fan was glad we ended up with Hendon Hooker.
We put ourselves through all this gut-wringing consternation speculating on things we don't control or yet have enough relevant data to understand. All these coaches, including Kim Caldwell, know what kind of player excels under their style of coaching. They know what skill sets are needed to excel in their style of play.
By this time next April, we will understand a lot more, just as we did with other Tennessee coaches after their first full season.