NBA Free Throw Mechanics Question

[ilyazhito]

In NBA (and G-League) games, you see the Slot official (Center official in amateur mechanics) administering the 1st of multiple free throws or an only free throw. This practice is not found at any other level of basketball. Where did it originate from, and why do NBA-affiliated officials do that? Is there any advantage to having the Slot administer the 1st free throw in a sequence, or is it just another attempt to be different from other leagues?

In the NBA Officials Manual (2018-19 edition), the Free Throw Attempts (Responsibilities) section says: "Line up the players as soon as possible. The official in the lead position will administer all free throws. You must make certain that there are two offensive and two defensive players on the lane lines before passing the ball to the free throw shooter. A third defensive player on the lane line is optional." Does the manual say that because no one bothered to update that section, or is it because the NBA Operations Department actually wants officials to do that? I'm curious, because all officials from the G-League to NBA Finals officials have the Slot hand off the ball for the 1st free throw, with no apparent backlash for not following proper mechanics.