I put this question out many a time. To me it is what keeps the celtics from being a great team. We've got the lock down defense, enough offensive players to score but our rebounding is bad. Who boxes out on our team? Pierce, Pietrus, Stiesmsa and at times, kg, rondo & bass.
To clarify I don't think Perk ever really boxed out much, now much picked on scal DID (really).
Its pretty simple, shot goes up get a body on closest opposing player. Basically our whole team is situation rebounders, ball comes to their spot they jump and get it. Pierce bless his heart at 6'7" when he's under the basket he boxes his man out.
Boxing out doesn't mean you have to get the ball just make sure your man doesn't get it. Defensive team has the advantage, right? We are closer to the hoop when shot goes up