We have been doing this drill for some time. And although I do know what it is trying to accomplish, I think it may be causing her to put too much weight on her rear leg, which is not what we want.
Although, I don't think she is loading like he does in the drill. I'm thinking a slight wedge under her rear foot might help her with the feeling.
"My weight is on my rear leg, as I start swinging, my weight shifts to my lead leg at the time of contact." - Babe Ruth
Swing hitting depends entirely on balance and timing. Note that my weight is on my left foot. As I start swinging my weight shifts to my right foot at the time of contact with the ball. The force of the swing makes a perfect follow through.