Okay I've had time to think about it, and I've decided I want to run it back.
Three trips to the conference finals and one to the finals in four years is really, really good, and you don't mess with that when you still have a young core.
Maybe fire CJM, but I'm not sure. If Brad thinks he's the guy and he's growing, I trust him. Plays after TOs weren't great, and I wonder about how they handled the zone. However, I don't blame the late game lapses on CJM at all--this has been a problem for this core with three different coaches--it's not the coaching, the team just needs to keep growing up.
Jaylen is going to cost too much, kind of, but he's the sort of player that is going to get this kind of deal. Unless you can deal him for someone as good--not two guys half as good, don't deal him.