I thought PPM had an influence on it. If somebody wants to learn "Dribble down the left" and his CA is 150, and eventually he learns it, his CA goes up to 155 or something. But that's just what I thought.
PPMs definetly cost CA. In my Milan save, i have Hazard and he had fulfilled his PA. Then i asked him to learn a PPM and his technique, crossing, composure and acceleration (??) all dropped by 1 point... Wtf?