You will find that her speed will increase to around 40-42. With good spin, I see rise speed start anywhere from 15- 20% slower than the fastball. Eventually it will improve to anywhere from about 5-15% slower.
The cool thing about a good backspin rise is that a mistake in spin results in a higher speed which helps keep it up.
The cool thing about a good backspin rise is that a mistake in spin results in a higher speed which helps keep it up.