Interesting concept here.
I don't think the point is counting how many balls are in each given area - it is obvious from a cursory glance that balls are clustered in certain parts of the court - no need to count the balls in the triangles IMO...It would be interesting to compare diagrams of one player over several matches, and from one player to the next to see unique or mutual patterns of play.
I disagree that nobody can hit topspin like Nadal - not perhaps with his power and expertise, but even rec players can use heavy topspin to great advantage and that's being taught by some of us, with specific techniques and purpose.
I agree it is also interesting how few balls are right at or on the baseline. For those who believe that a high percentage of shots land deep when watching a match live or on TV they must be focusing more on where the player is standing and how far back from the bounce the contact point is, not where the ball actually touches the court (as this charting suggests), but the speed of the ball is so great that it's difficult to see that.
How would you suggest incorporating it into coaching at different levels? Tape, cones, line markers (as those used for quickstart?) Would you go for percentages (ie: practice 10 shots per area until you get a consistent percentage level)?
I would also like to see the opposite perspective - where the ball lands and what the targets look like from the hitter's POV.
My first reaction is to keep it simple, perhaps with larger triangles at first that could be reduced in size as the player reaches a certain percentage of consistency, on a gradient. I will try it out myself.
Good work, 5263.