I agree with the foot work, heel first and toe pointed 12 or 1 o'clock, causing hips to square with the catcher. Her arm has to go around her hip. Either causing the ball to go inside or she may overcompensate and pull across and throw outside. I'm not a fan of closing the hips. Seems so many kids will have timing problems by closing too soon or a slow arm lagging the hips. My DD had the same problem with a long stride. She is 5'10 and just stepping off her stride it was over 7'. Drive leg could never begin to close/squeeze until plant foot landed. Shortened her stride by 6-8 inches and made a huge differnce. Back leg was squeezing(for lack of better term) to her front sooner/quicker and balanced improved. I tell her to stay open on most pitches but with all the momentum moving forward they do follow her arm, I just don't want hips closing before arm comes thru or hips swinging closed.I did not want her to slow anything or push off with any less force just drive the plant foot to a different spot. Nothing to back it up but my theory is that her stride was so long her momentum going forward was slowing before contact was made with her plant foot and caused less resistance to throw against. And feels like speed picked up with shorter stride, ormy imagination.