The way I look at it the back elbow keeps moving without connecting with the front elbow at the right time.
Her back elbow folds underneath to far.
Hope that helps
Not saying who is right or wrong.NewBucketDad,stand up take a few swings(can be a pretend bat).See how you swing a bat.Do you push the bat forward or do you whip the bat forward?.If you were to throw the bat,would the bat go further if you pushed the bat or if you whipped the bat?I prefer to whip the bat,throw the barrell,not push the bat.Take a look at Chas Utley's swing above.If you can get the bat moving like he does and teach it correctly I think you will have a hitter.This to me is one of the "Holy Grails"of hitting.Practice Chas's swing what does it feel like to you.Pulling of the hands in opposite directions?
Like elbows sliding across a table top. Does her Elbows slide across the table top for a few inches?
The front elbow will move 2-4 inches straight then like go up a ramp. Up and out.
When the back arm/elbow drives to far and past connection, normally the front elbow flyies out to fast and does not make a good first move.
Hitter has a way of explaining it to girls, better than me that makes them understand.
His first motto is keep it simple.
His second motto See it...Feel it...Fix it....
You could also think of it as maintaining the box.
The back elbow/arm starts then connects to the front arm and a box is maintained.
Some girls with the back arm too high slot it and keep slotting it, and the arms are straight at impact verses the box.
Most girls mainly the ones that are not big d-1 looking girls do not maintain the box with the back elbow that high. They seem to hit better with the roof of a house setup. It helps them to stay connected.
Bigger stronger girls seem to be able to hit with the back elbow higher. I think it is linked to forearm strength but that is only a guess by me.
Just a dad trying to learn.So this is what I learned.JMHO I like the higher back elbow while the batter "forwards by coil".I found in this hand set position the batter is then able to slot their back arm better.When the batter starts their swing they are able to turn the bat behind them not beside them.By that I mean if the batter was looking at a mirror with their body facing side ways of the mirror the batter would be able to see the bat knob as they turn the corner.If the batter had an A frame hand set and just went staright back and then straight forward the bat then would be turned beside them.To me this also feels like the bottom hand is in charge and pulling the bat forward.If I turn the bat behind me(corner)as I turn. I get the feeling of the top hand pulling down first,to slot the back elbow as I turn.As I turn the corner and the back elbow is slotted I then feel the top hand pushing hard to whip the bat.Feels like a punch with the palm facing up and pushing forward.The bottom hand is pulling, but it feels more of a guide hand.The top hand feels like if you were a catcher and you rotated your back arm(humerus 1 big word)to make a throw to 2nd on a steal.That is how I like the back arm to slot.Then to slot the back elbow you kind of just reverse it,like you raised it.Elbow leading on the raise of the arm,elbow leads on the slotting of the elbow.The bat head path would be making a reverse c behind you.The bat would be whipped behind you.That is how I see and feel it.I hope it makes sense.