It’s invisible, but make no mistake, it’s there. Generations of NBA players have had to encounter the Rookie Wall, so there was no reason to believe Mavericks No. 1 overall pick Cooper Flagg would be an exception. He wasn’t, as evidenced by his combined statistics of the past three games: 37 points on 14 of 47 (29.8%) shooting. As Mavericks coach and Naismith Memorial Basketball Hall of Fame point guard Jason Kidd explains it, the wall cannot be softened, easily climbed or ignored. “You’ve got to touch it,” Kidd said. “You’ve gotta rub it and hold it. He’s got to embrace it. That’s...