For my DD she struggled to throw strikes at 10U, but the moment she moved to 12U and started using the bigger ball and throwing at 40' it was like magic. Her strike percentage increased dramatically.
She was (and still is) a tall girl with big hands, so moving to the 12" ball was a much better fit for her.
She was (and still is) a tall girl with big hands, so moving to the 12" ball was a much better fit for her.