One of the characteristics of ball games is that players are expected to be able to respond to complicated and everchanging situations. For this reason, the methodology for studies of coaching in ball games should be different from that for experimental studies. We, therefore, propose the “retrospective” method for case studies about coaching in ball games. Such studies consist of the authorʼs daily practice of coaching. If some success has been achieved by an original approach, qualitative and quantitative data of the approach are collected. Data about the backgrounds of coaches and players are also necessary. Interpretation of the results of the approach is the most important point in such studies. It is necessary to interpret the results as comprehensively as possible. It is also necessary to convince peers by explaining bad as well as good aspects of the approach.