IMO, the barrel/bat lagging (wrist hinge) at around 90 degrees to the front forearm is released to 180 degrees(straight line with front forearm) to the palm up-palm down position. Some use a strong top hand and other a loose top hand. I prefer loose throwing motion.
Depends what you think the wrists are responsible for doing...
Some believe in a two launch approach; swing launch and barrel launch. The wrists are used to maintain control of the barrel until they decide to "release" the barrel into contact. The belief is that the wrists are used to enhance the timing window and make adjustments on the fly.
Others will claim there is only one launch; swing launch. Thought being that the barrel is launched in a direction towards the ball. The belief here is that the timing window is too short and the muscles of the wrists too small to have a significant impact on the overall process. There is still some room for adjustment, but not to the degree that the first group believes.
So, it comes down to cause or effect. Most believe that the barrel starts in a rotational fashion around the hitter and then moves onto a linear path "out from" the hitter's body. Do you believe the "out from" part requires wrist articulations at that time? Or are those articulations a result of things that happened upstream?
I believe the bats with moving weight in the barrel help with this. I made one hand bats out of PVC that Howard Carrier designed for this reason. The Whip Hit does the same.