When my DD was learning the horseshoe, she had the same issue. This may be obvious, but it helped her just to focus on turning the ball palm down earlier (between 12 and 9 o’clock). If she is late getting palm down and still leading with the pinky at 9 o’clock, that may be why she is behind the ball at release and only getting the knuckles to third when the ball is gone.Her issues is that on release she has her hand behind the ball and as a result she's not getting as much as a drop in speed or spin as she should. . .On video she lets go of the ball then gets her knuckles to third, if she holds on any longer the pitch comes out too high.