I find this mysterious. Getting the wrist loose enough and yet trying to control the direction of the bow is hard. When to use the fingers and when to use the hand is confusing.
Plus, all those bow holds. Texas fiddlers grab the bow underneath the frog with the thumb.
Rural fiddlers have their bow hold up the stick and not at the frog. Even some Irish fiddlers do this. There is a German bow hold flattening the fingers on the stick, a Russian bow hold where you grip the stick with the second knuckle of the index while balancing the stick with
the middle finger and pinkie, a French bow hold where you grip the stick with the first knuckle and balance the bow with the middle and pinkie. Some bow with the entire arm and some with just the wrist and minimum arm movement. Some use detached bowing and others use a long bow with hammers and pulls in the left hand. Then there's the shuffle bowing, the Georgia style, the Tommy Jarrel style. Some use the full bow and some like certain jazz players (Stuff Smith) just use the upper middle area of the bow.

It's all very confusing.

Frank