As far as I can tell none of the zone defenses are a true 'zone'. In any of the defensive selections the match enginge still plays the defense as man-to-man. What the zone defenses do is provide a boost to certain aspects.In a 1-3-1 the PG will still guard the opposing teams PG, the SG will guard the SG and so on. The difference is that everyplayer will receive a large boost in their Outside Defense skill while suffering a penalty to their Inside Defense and Rebounding skill.I am not 100% certain of this but I am fairly sure. If you watch the match viewer during games when you are playing zone you can notice that if the other teams Center happens to shoot a 3 it will mention that he is under pressure from your center. Same with a PG going for a lay-up, this leads me to believe that defense is always man-to-man.
Pg into 1SG C PF into 3SF into 1 cause he needs to run from side to side of the triple zone, and centers will be to slow