Pick and Roll Follow Up, Posting Up

[TigerBball]

Been on vacation, read through the whole pick and roll thread and still unclear. This is what I think is being said. If my guy sets the screen, contact is made, and then rolls keeping contact without displacing the defender who has given up on the play, it is OK. If the defender is trying to spin around the pick and my guy rolls into his path after contact, no OK.

But now this brings on another thought. When does the pick stop being a pick and start being a post up. You see guys posting up and displacing the defender all the time. Is this action legal.

Finally, in my next game, do you think it would be wise for me to say, "hey ref, that's not a foul, he was not doing a pick and roll, that was a pick and post up"