Sorry to ask (I could sound really stupid) but what do the blue dots mean?
This is one of those important times to distinguish between "possessions" and "disposals"
You can take possession of the ball, and not dispose of it. (eg get tackled)
You can dispose of the ball, and not take possession of it. (eg kick it off the ground)
McGovern's heat map is proof, that these are possession, not disposal maps. He kicked a goal out of mid air, 2 metres from the goal line, but as you can see, he has no blue dot near the goal line. He never actually took possession of the ball. This also explains why you will see a discrepancy between blue dots, and disposal counts.
McGovern
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EDIT-Landscape heatmap
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