I guess I am surprised that anyone is surprised by this. Trev was in a no-win situation. He had to make certain he exhausted the "every chance for success" from his administrative position. The key issue could have been that Trev had not been there long enough to verify all of that and to install his form of support for Frost.
To me, this is all classical administrative/staff support with some twists of contracts of course. Next year is going to be massively heavy on Frost and his staff. No way around it, he has been painted back into the corner with support all around and everything pointing right at him.
As for the coaches leaving, I have been asking for some heads based on obvious poor coaching of technique but even I was surprised at the number sent packing. It simply had to happen and should have occurred two years ago, it was so blatantly obvious at least to me.
I will also continue to bang this drum, but Frost needs some experience in this coaching staff. There is, in coaching terms, a lot of youth there. There is something to be said for those coaches who have tested over time and can see what is going on in a nano second and not keep doing the same old thing and expecting different results.
In the end, as they say, the devil is in the details and so far, this program has not shown much attention to that. That, perhaps, is exactly where Frost is weak.