JB, Very much agree with your statement. I actually spent a lot of time working on this very concept with our indoor cages over the winter. The idea of hitting the back of the cage was replaced with a power zone (green tape) that wrapped the cage including both sides and the top near the back. Using the concept that allows you to play a video golf course indoors I watched BP for weeks making notes of vertical ball direction, and horizontal angle.
I then started with a line drive that would first hit at the edge of the outfield grass and went to a ball hitting the base of the fence and marked it green. Then I isolated lowest area where the sharp down angle results in ground balls, marked that in yellow and areas where the outfielders would get easy fly balls, (they show up as oval red tape) power ally's were green to a point and then yellow above and then there is more red tape in close to the batter where pop flies live.
In addition to regular BP where it provided some indication of ball travel for the coaches we also added an "Extra session" if anyone wanted to stay late
Rules were simple, square up the ball and hit it sharp (If you don't, it is an out, Green is 2 points, Yellow is 1 point, Red is an out, 5 points is a run, 3 outs an inning coaches discretion.
Every single player stayed and had a blast...Some great progress over the winter looking forward to how it translates outdoors.
freddy77 you make a great point, so i wanted to clarify this was not about directing just trying to provide some instant feedback that indoor cages often lack....