I think they reeved the block while it was sitting on the front deck, and then he simply boomed up, causing it to swing out. We always set them on the ground right under the lowered boom tip, sometimes with the front outriggers retracted with the back ones tipping the boom as low as it can get (aka where we can reach it). A simple tag line would have prevented that (pun intended), as would booming up if the block would feed line (likely no). Basically it was being run by people with no damn clue