That tee is forcing her downward barrel path. It doesn't allow her to turn the barrel down behind and up through the ball. The ball is coming to her on a downward plane from the pitcher. We want the barrel of the bat matching that plane by coming slightly upward towards to contact. Thing of the path of the barrel as a Nike swoosh. That path is impossible with that tee.
That's been a concern of mine ever since I was given that tee by a friend who's DD quit the game. 90% of the time I use it turned the opposite direction with the flat arm out front.