For Jameer Nelson, the moment arrived before Jacque Vaughn had coached a game. Nelson, then the Orlando point guard, was working out in Pennsylvania in 2012 shortly after his Magic announced the 37-year-old Vaughn would be their new head coach. Vaughn, just three years after his final game as a player, felt a need to sit down with a veteran he saw as a leader, so they grabbed dinner in Philadelphia. “He said, ‘Look, I’m going to lean on you,’ ” Nelson relayed over the phone Thursday. “ ‘I want you to be involved. I want you to help me....