Dragging the target to where you are aiming accomplishes two goals: First, it lets the analyzer color-code your after-game pictures. Second, it lets the analyzer figure out how good your aim is, which will (hopefully) help you figure out where to aim to increase your scores and accuracy.
Both darts and targets have a label that always shows where the pointer is — the target above is pointing at the double bull, and the dart is in the 13.
Too lazy to drag the targets? So am I! That’s why you can just tap on the dartboard and the next available target will center itself on the nearest region’s center.