I definitely think the rudder is her big issue. Need to work on the posture to rid herself of the very slight lean to the right. That slight lean allows the arm to pass without the proper brush interference. I can see a couple mph with these basic corrections.Hi cv,
Sure, your spot on. The furthur past 45 the plant is, the more the knees, hips, torso and shoulders have to adjust to the plant foot in the very same direction. The mechanics become both less efficient and less productive and usually introduce posture issues which can have a negative effect on speed, accuracy, movement. The greater the plant beyond 45, the higher the chance of counterproductive inefficiencies. You mentioned ruddering, and there's also the gluteous kickout, introduction of pushing the ball rather than pulling and whipping the ball down through release just to mention a couple.
So in pitching, it's natural to start open, plant to a degree closed and then finish open again. The furthur the plant deviates past 45 toward 90 degrees, the greater the fight to find balance (and sometimes struggle or won't) and get back to open again.
Remember, order comes from geometry...curves, angles and patterns.