This. The marker moves based on how the ball is hit. Balls down the line will always drift closer to the line (or past it). Hard hit balls to center(or left-center, or right-center) will always drift back closer to the wall (or over it).
Then you have cue shots that will drift sideways away from the hitter (towards the right from lefties, etc...) and what have you.
Just keep practicing and you will get it.
For optimal practice, play exhibition in Tampa or Toronto, or turn Wind off. That way, the type of hit is the ONLY thing affecting the drift, and you will get a better feel for how to predict it.
I've only lost but one fly ball, and that was my own mistake, not paying attention and stuff. It's really not an "issue," nor does it need patching, at least not in my opinion.