Figure 3. The visible evaluation model of the tactical benefit of the third to fifth strokes in the service round. The median tactical frequency and scoring rate in the tactics of the third to fifth strokes are 0.021 and 0.526, respectively. Therefore, the tactical benefit value ranges of the four areas are (0.054, 5]; (0, 0.054]; [-0.054, 0) and [-5, -0.054), respectively.