established legal guard position but too close to an opponent without the ball?

[Adam]

From the sounds of your play, it seems like a player control (offensive foul). Once A1 catches the pass, time and distance become irrelevant. If, however, A1 crashes into B1 before catching the ball, then time and distance matter and A1 must be given one or two steps from the time B1 establishes position.

The question is, essentially, is this a screening play or a guarding play?
The answer is determined by whether A1 has the ball when contact is made.