55/57 mph is really good and is above average for her age in most places.
As said above continue to improve on core and leg strength. The unofficial number to introduce a rise ball into her arsenal is typically 55... So, in my opinion a rise is due. Even if blue isn't calling them, it's still hard for a lot of batters to lay off a ball up in the zone.
Has she spent any time with a rise thus far?, like learning the grip, slot, or posture?
As said above continue to improve on core and leg strength. The unofficial number to introduce a rise ball into her arsenal is typically 55... So, in my opinion a rise is due. Even if blue isn't calling them, it's still hard for a lot of batters to lay off a ball up in the zone.
Has she spent any time with a rise thus far?, like learning the grip, slot, or posture?