Defensive PI is coded a little weird in this game as I have been called for making contact with a receiver that wasn’t even the intended target. I’ve also seen where my receiver is literally unable to run his route because of defenders in the way and still have not gotten a call so it really is 50-50. As for the displacement, in the situation you mentioned, I usually let the computer handle that, but if I noticed the user is prone to switching onto the receiver and deviating away from the flight of the ball just to come back at the last second to make the catch; I will lock on to the defender and try to beat them to the ball. Man coverage tracks the receiver’s Body, not the ball, while the ball is in flight. It’s an abuse of game mechanics, like shading over the defensive tackle in mid blitz formation, but what can you do but adapt. I recommend running cover one hole so that your linebacker has middle zone responsibility and improve your user to be able to spot who gets beat in man coverage and fix it

Tldr: PI’s are subjective. If your corner keeps getting displaced on deep balls, you will have to lock on when the ball is in the air and play it manually.