The shorter steps are for decelerating in order to set yourself up. They get you into position.
Then once you're in position, or where you've determined you can set up for your shot well enough, plant your back foot behind the ball, putting you in an open stance behind it.
It should help THAT much. The shuffle steps get you into position, but they don't include your stance.
From your foot planted behind the path of the ball you can either rotate your trunk and step into the shot for a neutral stance (or semi-open, which I prefer most) or keep it planted in your open stance.
Don't think of the last part as a "big step". That way you think of it as still moving, not starting to prepare, and you just run into the ball. It's important to distinguish between moving and preparing, at least for me.
Well, that's just the advice that helped me understand it, hopefully I conveyed it okay.
