herne79:
Player Traits (formerly called PPMs) don't overwrite Player Instructions. Complimentary Traits and PIs intensify the effect, contrasting ones dilute the effect.
A player's own ability may also have an effect, so for example a player with poor dribbling skills and decision making who has the Trait "runs with ball often" probably won't be able to carry it out very well, whereas someone such as Messi will.