I was taught to freeze and listen for a teammate to direct me ( in CF, presumably the LF or RF can see the ball). I suppose it might be harder to hear a teammate in a stadium with 35,000 screaming fans than an empty field behind a high school. He can also take a quick look around at his teammates to see where they're moving. If the LF is racing toward the wall in left-center, or the SS is tracking back into short center looking up, that could be a clue as to where the ball is going. I know when I'm at a game, I'm watching the fielders rather than the ball when it gets hit.By the way, what’s best practices for an outfielder losing a fly ball? I’d think you’d want to retreat as far back to the wall as possible to keep the ball in front of you and be able to run into the throw, but I haven’t played since high school.