@mayjay Regarding Self, by appearances, he is very calm with Grimes vs. what we saw with certain players say 3-4+ years ago. I could understand, then, why Anrio Adams (or whomever) might be a bit gun-shy. But not with Grimes. I don't think Self has much to do with this (understanding we don't know what goes on in practice). By appearances, Self is reactively patiently. (I know you didn't mention Self, but it's a good place to start).
But it does appear to me that he's hesitant -- and then not. Hesitation in athletes, many times, comes from being unsure. I personally think that's it. We don't know the combination of factors causing it, but I also think he has the appearance of a guy trying to avoid mistakes. But that's not saying you're incorrect. I think you're right as well. I think his fear of mistakes creates hesitancy, and thus we see some of the things we discuss. Then, he overreacts, listens to what everyone is telling him -- he says to himself, "I'm just going to play." Then he makes another stupid mistake because his throttle is too far open -- like the silly charge at the end of the game.
So I think it's chicken or the egg. Perhaps the "I'm just going to play" creates an overly-loose style first, and then when it blows up, he retracts. That may be more plausible in the cause/effect now than earlier. Because now he's probably going into games saying, "Relax, just play the game." And then two turnovers and offensive foul later, he reverts to survival mode (trying to stay on the court).
That may be some overdone psychoanalysis, but I think it's a reasonable explanation.