Many years ago I asked one of my esteemed colleagues why he left his A+ university for my university, at that time not an A university. He mentioned that the department had fallen apart, the chair drowned and various people had peeled off. He probably liked coming to LA from someplace less attractive, as well. Maybe it was a chair or money, I do not know.
It's very difficult for a department to stay strong unless it has good people, it supports them well, it makes those people feel wanted, and it brings in more good people. You, as a dean or provost, cannot afford to delude yourself about quality, because your faculty surely knows what's up. Not everyone is drinking the Kool-Aid.
You live in a competitive university environment, the people likely to be bid away are very strong or very promising or both. They are not inexpensive, yet they respond well to having a cohort of colleagues who are very strong. It's more likely you will be able to grow or at least remain stable if you realize that mistaken appointments are corrosive, even one will be noticed. When you hire junior faculty, they need to be people who are ambitious and hard working, and who want to be like their most esteemed colleagues. And they need to be supported, not used up with stuff that prevents them from growing. If your teaching loads are larger and support is weaker than those you'd like to compete with, you will lose people you want to keep.
Now you might want to move from C to B or B+. You still have the same issues, although most B or B+ people are not likely to be bid away. On the other hand, can you make them more productive, more effective? If you do not have the resources, and you expect to squeeze them out of your faculty, you will again have people leaving, and not be able to make the best out of your faculty.
There's no simple answer if you are resource poor. But it helps to have an realistic estimate of your quality and attractiveness, to be in the game rather than on the side. And to have a strategy where you can occupy niches that are important and otherwise ignored.