Let's assume your form is perfect and the arrow still hits a little to the left, and you're a RH shooter. By softening the side plate you can move the POI a few inches to the right at 20 yards. In other words, if your side plate is plain leather, you can peel that off and put Velcro on instead. If your side plate is Velcro, you can peel that off and put a rug rest on instead, such as a Martin rug rest.
No bow is the same as any other bow, and it is convenient to be able to move the POI so it impacts the same as other bows you're used to. Of course, if you move from a contoured grip recurve cut past center to a broom handle longbow cut to center, you're just going to have to learn a new way of shooting. But in moving from one bow to a similar bow, it is helpful to make small adjustments so both impact in the same place.
Everybody above is also right, of course. Once I learned how to actually come to full draw, my arrows suddenly started impacting right, and I was replacing my Martin rug rests with Velcro to go the other direction.