Hmmm...now I am wondering: If the defender leaves his man to go help out somewhere else, is he still a "primary" defender on the guy he left?

Over-thinking it???

Maybe I've misunderstood that rule. But just how big is the LDB in NCAAW? The drive started from the free throw line. So assuming that this were NCAAW and that the defender hadn't been moving forward at the time of contact and that whatever interesting stuff about secondary primary defenders didn't apply. Would this not be a block in NCAAW? I thought it went out to the second free throw space.

It does. I didn't go back and look at the play / drive when responding to the question.

Thing is I don't know when a primary defender becomes a secondary defender or vice versa. I would like to say that any player that starts inside the RA and tries to establish position outside the RA in order to draw a charge should be considered a secondary defender. Obviously there is some common sense involved, but perhaps there should be a distance requirement for maintaining primary defender status in relation to RA plays.

As Justice Potter Stewart says, "I know a secondary defender when I see one."

Help then comes back
 

I think he is a secondary defender. When he moves over to double team the player on the low block, then comes back he is a secondary defender in my opinion. Good call, good teamwork by crew.