The worst a new leader can do is come and do stuff halfway. If you are wanting to establish a new culture, style of play, loyalties etc. you can't keep the old guard around. The assumption is that Sam might have helped in the portal but even if true, the short term gains may not be worth the long term costs.
I suspect the players CKC brings are going to seen as underwhelming by the fan base. She ain't getting a Kiki right now so they will be probably be athletic, mid major types that the new system and philosophy.
CKC probably waited a bit to make this change because everything was such a whirlwind and she needed to get a few things in place. Kinda surprises a similar news has not dropped about Joy but I would expect it to be coming soon.
Update: Brooks dad posted his unhappiness about this move so i think we can assume the Nyla ship has now sailed.
Obviously, CKC has a vision now time will tell...