I agree with mersk. Although I signed van Nistleroy for my Swansea side first season as reserves manager and he had average coaching attributes (all tens except ones for goalkeepers and fitness) and top class DDM. Now a season and a half later he's one of the best coaches in the game world. So sometimes you've got to spot the potential. For that you need high DDM (especially determination) and high tactical knowledge and/or good JPA and JPP can be useful useful. Also the less qualified the coach, the more potential.