What to look at
There is much more in an overhead cast than most can see. In these shots, look at the angle of the rod. A spey caster is used to angle down is arm more than an overhead caster.It doesn’t change anything at the rhythm and form of the cast. The Line is completely deployed on the back and on the front before it is let land on the water.
I show the 3 possibilities of casting. Depending of your biomechanics and musculature, your arm will be strong either in wrist, forearm or upper arm/shoulder.
If you have learned with a book between chest and elbow, you are cursed to use the first and hardest solution: the elbow is not moving all the cast are performed with the forearm.
But there are many chances that you could resist and your elbow came up, and you cast now with your biceps and arm.
If you are stronger from shoulder, it is sure that you cast arm up, it is the solution with the larger amplitude.
There is no good way, in my humble opinion. Most of the cast is timing and second, form.
In the last shot, you can see the back cast and the line is completely deployed. It’s one of the most common problem. you can see. Most caster don’t wait long enough and come back to fast. It is “castus interrompus”, it doesn’t give you all the joy.
The only hint and most important one is straight up your rod. Whatever you do, I’m sure your rod is angled down. You don’t wait enough, you come back too fast but your worst problem is that your rod is not vertical enough.
Remember : far from the eyes, for from the vertical.
Think only to this and your loop will closed themselves.