That's what I said. It looks like the head moves back more on the lower pitch than on the higher one!
I noticed that, also. I believe it is the result of the swing, though, not the cause. IOW, I believe it is the result of her intentionally trying to lift it. In itself, not a flaw. But she also needs to learn to hit line drives, ground balls, etc., when called for.
A lot of players (most?) have never been taught how to hit on demand. I hear people talking about hitting opposite field, for example. I see far fewer actually teach it. Same for fly balls. I recall very few teaching how to hit fly balls—quite the opposite, in fact. A player needs to be able to execute what is needed to produce runs. If a coach wants a sac fly the player must be able to reasonably execute. If they've never been taught and practiced a skill how can they be expected to execute that skill?
This player has a pretty nice looking fence swing. Keep that ability, but add to it!
That was my point - she is intentionally trying to lift everything. The OP is looking for suggestions to level out the ball flight. I would start with a more stable head going into contact.
I might try setting up a tee about 3' 4' away from a fence. Have your DD hit balls into the fence. See if balls go high, low or straight into the fence. Adjust as needed. A lot can be learned about a swing by just hitting into a fence. Learned that from Straightleg, Howard/Hitter and Sbfamily.
Not sure how a more stable head would stop someone from intentionally trying to lift everything. I suggest trying techniques other than lifting if the lifting is undesired.
The key word is intent. If it was unintentional that would call for a different solution. If she's doing it on purpose and doesn't want to be doing it the solution would be to try something else.
Have you ever hit defensive practice and tried to lift the ball high for pop ups? What does your head do? How about when you try and hit grounders or line drives - does your head move in the same manner?
Again, I think you're talking about the result of an action—not the cause of the action. My head may lean more backward if I try to lift it high but I would not lean my head back to begin the swing.
It sounds like you believe she is leaning back to lift the ball. I believe the lean is a result of her trying to put more power into the swing.