That's where I would say that he's not a good head coach, because a good head coach knows when to let go of the reins, as he's already surrounded himself with a capable supporting cast.
That doesn't mean that O'Brian can't be a good head coach, even a great one, yet his progression is slow if that's his trajectory. He really hamstrung himself those first three years. That's on him and whatever Rick Smith brought to the table.
Now, we are into his second batch of three years (I break a coaching tenure into three-year chunks). After this year, if he hasn't learned enough to get an OC, yeah, I'll be manic for his head on the chopping block. Indeed, I'm almost ready for him to go, this very minute, as those first three years are still playing out today.
In other words, with an OC, it's still going to take a miracle for me to put my trust in him, short of him leading us to a Super Bowl this year, or the next. Coming close is not good enough by year 6.