Our PC teaches my DDs to step to the left of the powerline to throw outside to a RH batter and step to the right of the powerline to throw inside to a RH batter. The exception is the screwball - where the instruction is to step left and spin the ball back toward the batter.
Stepping left of the power line does not make the ball go inside to a right handed hitter. Lets assume two things. (1) The release point of the pitch is perfect and the pitcher is throwing a straight doorknob fast ball (no Magna force). Then the ball will then follow the line of her hips. (generally speaking) As someone already mentioned, step left throw left, step right throw right. The problem you may see is when the the pitcher steps left and leaves her hand / release point behind or late on the hip, thus preventing a finished spin. The wrist snap/fingers end up not being finished forward, thumb will appear to point inside not forward. Results look similar to a screwball, but not a good one. You will find these pitches are typically too far inside, not repeatable, and usually lower and slower than the properly released screwball.
if the hips are turned at an approximate 45 angle to the plate/batter, how does this work - "Then the ball will then follow the line of her hips." ? I'm trying to figure these inside/outside pitching mechanics. wouldn't foot placement be a large part of it? honest questions here.