I'm concerned when officials aren't aware enough to know when a ball shoots out of bounds. I don't need to see it to know it's out (and blow a whistle).

Interesting, Very Interesting ...
 

Devil's Advocate here: In IAABO two person mechanics, the sideline boundaries are the responsibility of the primary coverage area officials, but on the front court endline, the lead has responsibility for the entire endline, even the portion outside of his primary coverage area, while the trail has a primary coverage area that does not include a frontcourt endline boundary responsibility.

Goose-gander?

Umm, who is responsible for the backcourt endline?

That gives the Trail 3 boundary lines to deal with: his sideline, the division line, and the backcourt endline.

Fish, Or Cut Bait ...
 

I'm playing Devil's Advocate here:

... The trail, because it's in his primary coverage area, as is the division line, the near sideline, and the far sideline above the free throw line extended. A small portion of the frontcourt endline is also part of the trail's primary coverage area, but he's not responsible for the boundary line there.

IAABO took away the lead's sideline boundary above the free throw line extended because it didn't want the lead ball watching. But it wants the lead to ball watch when the ball goes out of bounds, or a player steps on the boundary, on the entire frontcourt endline, even though a portion of it (the far side) is outside the lead's primary coverage area.

As the lead, if I'm watching for the legality of a weak side screen in the paint, how can I also watch for a player stepping a half inch on the frontcourt endline when said player is all the way down in the opposite corner, dozens of feet away from me, and several feet outside of my primary coverage area (again, Devil's Advocate here)?

Does IAABO want us to call boundaries in our primary coverage areas, and not ball watch, or does it want to give us some simple boundary responsibilities, like the good old (IAABO) days, and not have to mentally debate whether, or not, the out of bounds violation is above, or below, the free throw line extended?