I'm gonna throw this out and see what people think.
In 2-whistle there are two issues that negatively impact the lead's ability to call the "over the back" on rebounding action in the paint.
First is the sheer number of bodies. There are usually 4-6 bodies there, often 8, sometimes 10. That can make it difficult to clearly see beyond the first 2-4 players in front of you. And it's impossible to focus on that many people, all of whom may be working for position.
Second is the angle, for rebounding action across the paint from the lead, the lead is often straightlined and would be guessing whether there was contact.
A third (at no extra charge
) is how close the lead is to the action. If he has closed down, he will likely be close enough that the action fills most of his field of vision.
On rebounding situations,
the trail has to be aggressively refereeing the action in his half of the paint. This frees the lead to focus on his half which helps alleviate issues with the number of bodies and straightlining, and to a lesser extent, the field of vision issue.
But the trail also has to work smart. He's got to work for an angle that will allow him to see everybody in his half of the key and to avoid the straightlining.