That would be nice. But in most cases when a defender is not beaten by the receiver and plays the ball, even if there is a collision there is usually no flag thrown. So the key is: not getting beat by the receiver and make an attempt to catch the ball, not just whack the receiver before the ball gets there.
It used to be that if the DB did not turn his head or make an attempt to turn his head it was DPI. Why that went away I don't know . DPI needs to be more defined