I'm fine with it. The hand is being pulled back to the chest in the "shadow" of the mitt, just like she has been trained. In that position, there is a low chance of a bounce off the ground hitting her hand, but not a direct shot from the pitch or a foul ball. Also, this keeps her hand in a position for a quick transfer in a throwing situation.
Here's earlier on the same pitch...
O okay, that makes sense. Next question...what's with the fence extension behind the batter? Is that to intercept foul balls from going out of play? I know the perception is screwed up from the photo angle, but it appears it could be "in play" at times. Looks like the end is hovering above the base line. Never seen this before.